Blueberry Eclairs

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This blueberry eclairs recipe is super easy and perfect for when you want to whip up something impressive in just an hour and a half.

Recipe At a Glance

There are dozens of ways to make blueberry eclairs. My method to make this French dessert is simple: fill the eclairs with blueberry mascarpone cream and top them with blueberry ganache.

The cream and ganache are easy to make and take about 40 minutes to prepare. You can start prepping them while the eclairs bake, then finish while the baked French pastries cool down. After that, all that’s left is filling and topping the eclairs, and they’re ready to eat.

This eclair recipe is simple, making it a great option when you need something that looks impressive, but you only have about an hour and a half to finish it.

Making blueberry eclairs for the first time? Please read the ingredients notes, step-by-step instructions, and tips. If you’re familiar with the recipe, feel free to jump to the recipe card.

Ingredients Notes and Substitutes

Eclairs

• Water and milk: Full-fat milk works best, but skim will work in a pinch.
• White bread flour: This flour is ideal for making eclairs with the fewest holes, making piping easier. All-purpose flour is a decent alternative, but you might have a few leaks when piping the cream. It’s not a big deal, but not ideal either. Use white bread flour if possible.
• Unsalted butter.
• Eggs.
• Salt and sugar: Sugar alternatives are perfectly fine.

Blueberry Mascarpone Cream

• Blueberries: Fresh or frozen. I use frozen because they’re cheaper and available all year round.
• Granulated sugar.
• Lemon juice: Helps balance the flavor of the blueberries.
• Mascarpone cheese: Stabilizes the cream and adds a ton of creaminess. You could use cream cheese, but mascarpone is the better option here.
• Heavy cream: Use the brand you use for whipping.
• Powdered sugar: Adjusts the sweetness of the prepared cream.
• Vanilla extract: Optional, but enhances the flavor.

Blueberry Ganache

• Blueberries: Fresh or frozen. I use frozen because they’re cheaper and available all year round.
• Sugar.
• Lemon juice: Helps balance the flavor of the blueberries.
• White chocolate: Couverture chocolate is the best option, but any white chocolate should do fine.
• Heavy cream.

How to Make Blueberry Eclairs

Before we start, let’s go over a high-level game plan.

Here’s how we’ll go about it:

1. Prep choux pastry and bake eclairs: Baking the eclairs and allowing them to cool a bit before piping gives us enough time to make the filling and topping, so we start with that.
2. Cook blueberry sauce: This sauce is the base for both the ganache and mascarpone cream. It’s a thickened puree packed with blueberry flavor. We need it thick so it doesn’t add too much water to the mascarpone cream and make it liquid instead of creamy. You can cook the sauce earlier in the day or even the day before.
3. Make blueberry ganache.
4. Whip blueberry mascarpone cream: We make it last because the blueberry sauce needs to be cold before we can add it to the cream.
5. Pipe the eclairs and top them.

Let’s dive right in.

Step 1: Make and Bake Eclairs

(Read my articles on choux pastry and eclairs for more tips.)

1. Preheat oven. Preheat your oven to 390°F (200°C).
2. Melt butter and bring to a boil. In a pot, combine butter, milk, water, salt, and sugar, then bring the mixture to a boil, ensuring the butter is fully melted.

3. Add flour. Take the pot off the heat, add all the flour to the mixture at once, and stir until it roughly combines. Bring the pot back to the stove and continue stirring with a spoon over low heat. The dough will thicken and clump quickly, but you should continue stirring the mixture for 2-3 minutes, ensuring all the flour is incorporated and no white floury spots are inside. While stirring, scrape the dough from the sides and bottom to prevent sticking. After 2-3 minutes, the dough should be glossy and easy to detach from the pot, and a thin layer, or film, should form on the bottom.

4. Transfer. Move the dough to a mixing bowl and let it cool for about 10 minutes. Spreading it across the bowl can speed up cooling.

5. Prepare eggs. Crack the eggs into a separate bowl and whisk them.

6. Make dough. Once the dough has cooled slightly, start mixing it with a hand mixer at medium speed. After 20-30 seconds of mixing, add half the eggs to the dough and mix until incorporated. Repeat by adding half of the leftover egg mixture. Now it’s time to get the dough to the right consistency: you want it thick enough to hold its shape but still pipeable. The V-Shape test is the best way to check for that: Dip your mixer whisks or spatula into the dough and lift it. The dough should slowly fall off, eventually leaving a piece of dough hanging that forms a characteristic ‘V’ shape or a triangle at the end of the whisk or spatula. If the dough is not there yet, continue adding the eggs bit by bit and checking the consistency.

7. Prepare baking tray. Line a baking tray with parchment paper or a silicone mat. If you could use a guide for piping, draw straight 4- to 5-inch long lines (or 2.5- to 3-inch ones for mini eclairs) on the underside of the parchment paper as a guide, spaced about 2 inches apart. That will help you make the eclairs straight and of uniform length. Some baking mats already have the eclair shape on them, so consider buying one if you often bake eclairs.
8. Piping prep. Transfer the dough into a piping bag fitted with a large tip. I use a Wilton 6B, which has an opening of approximately 15mm in diameter (a bit more than half an inch). Alternatively, use a plastic food bag with a corner cut off.
9. Pipe. Pipe the dough onto the prepared baking tray, forming strips about an inch wide and 4-5 inches long (or 2.5 to 3 inches for mini eclairs), leaving more than an inch of space between each strip to allow for expansion. Hold the piping bag at a 45-degree angle and pipe the eclair in one slow and smooth action. If the end of the eclair has an irregular shape that bothers you, you can smooth it out using wet fingers.

10. Brush. Melt a small knob of butter in the microwave or on the stove and brush the eclairs with it. Alternatively, substitute with a light coating of non-stick cooking spray for convenience. Both options are fine.
11. Bake. Place the tray in the preheated oven, then immediately reduce the temperature to 356°F (180°C). Bake for 40 minutes (35 for mini eclairs). Open the door a tiny bit (and leave them open) for the last 5 minutes for any buildup steam to escape. If the eclairs start to brown before the 35-minute (30- for minis) mark, lower the temperature to 320°F (or 160°C).

12. Cool. Remove the eclairs from the oven, let them cool for 10 minutes, then carefully detach them from the parchment paper or silicone mat and let them cool on a wire rack for another 10 minutes before piping and filling.

Step 2: Cook Blueberry Sauce

1. Cook blueberries: Place the blueberries in a medium saucepan (wash them first if using fresh), add one tablespoon of sugar from the measured amount, and put the saucepan on medium heat. Cook until the blueberries break down, release their juice, and the mixture boils, stirring occasionally.

2. Strain: Strain the mixture into a bowl using a mesh strainer, pressing the blueberries with a spoon or silicone spatula to extract as much juice as possible. Discard (or eat) the skins.

3. Thicken: Return the blueberry puree to the saucepan and cook over medium heat, stirring occasionally, until it thickens to a spoonable consistency, similar to a thick compote or soft jelly. This typically takes 8 to 15 minutes, depending on the pot size and amount of blueberries (e.g., if you’re doubling the recipe).

4. Add lemon juice and remaining sugar: Once the sauce is thickened, add the lemon juice and remaining sugar and stir to combine. Taste and adjust the flavor with more sugar and/or lemon juice as needed. Cook for an extra 1 to 2 minutes, then remove from heat.
5. Divide: Divide the prepared blueberry sauce into two portions: transfer two-fifths of the sauce into one container and the remaining three-fifths into another, maintaining a 2:3 ratio. A kitchen scale is helpful here, but you can also do it based on volume. Submerge the larger portion in a bowl of cold water to cool it quickly for the mascarpone cream. If making the sauce in advance, let it cool, then refrigerate it, and divide it only before starting the ganache.

Step 3: Make Blueberry Ganache

1. Prepare the double boiler: Fill the bottom pot of the double boiler with about 1-2 inches of water, ensuring the water does not touch the bottom of the top bowl when placed over it. Place the bottom pot on the stove and bring the water to a gentle simmer over low to medium heat.
2. Add chocolate and heavy cream: Chop the chocolate into small, even pieces or divide it into squares using your hands. White chocolate melts easily, so precision isn’t crucial. Place the chopped chocolate into a heatproof bowl and add heavy cream. You can bring the heavy cream to a boil before adding it to speed things up, but that amount won’t be enough to melt the chocolate entirely, hence the double boiler.

3. Melt the chocolate: Place the top pot or bowl over the simmering water. Make sure the bowl fits snugly and does not touch the water. Stir the chocolate every two minutes or so until it melts completely and combines with the heavy cream.

4. Add blueberry sauce: Add the blueberry sauce reserved for the ganache (the smaller portion) and stir to combine.

5. Take off the heat: Remove the top bowl from the double boiler, carefully wipe its bottom, and set aside. Leave the hot water in the bottom pot for now, as you might need it to warm up the ganache if it gets too cold to top the eclairs.

Step 4: Whip Blueberry Mascarpone Cream

1. Whip heavy cream: Pour the cold heavy cream into a cold bowl, add powdered sugar and vanilla extract, and whip on medium speed until the mixture doubles. The mixer whisks should leave a momentary trail behind them but stop before reaching the soft peaks stage.

2. Add mascarpone cheese: Add mascarpone cheese to the whipped cream and mix on medium speed until the frosting is firm and smooth. This happens quickly, so keep an eye on it. Stop immediately if the frosting starts becoming grainy.

3. Add blueberry sauce: Add the cold blueberry sauce reserved for the cream (the larger portion) and whip the cream on low speed for a few seconds until combined. If the cream starts becoming grainy before adding the sauce, stir it in using a spatula instead.

4. Taste and adjust: Taste the cream and stir in more powdered sugar if it’s not sweet enough to your liking.
5. Refrigerate: Refrigerate the cream until you’re ready to pipe the eclairs.

Step 5: Combine

1. Prep eclairs for piping: Grab a small round piping tip and gently poke three holes (two for minis) in the bottom of each eclair, ensuring the hole is large enough for the piping tip to fit. Alternatively, you can make similar holes using a paring knife. These holes will help us pipe the filling inside the eclairs. If you prefer, you can slice each eclair in half horizontally using a serrated knife, creating a top and a bottom.
2. Pipe eclairs: Gently fill each eclair with the blueberry mascarpone cream, stopping when the cream starts coming out of other holes or any cracks in the eclair. A decorating syringe works well here, but a piping bag with a tip also works.

3. Top with the ganache: Pour the blueberry ganache into a bowl large enough to dunk the eclairs in, and dip the top of each eclair in the ganache, smoothing any excess with a finger if needed. If the ganache is too thick, warm it slightly in a double boiler until it’s usable again. If it’s too thin, cool it in a bowl of cold water until it’s thick enough to stick to the eclairs.

4. Decorate: Decorate with fresh blueberries if you have some on hand.
5. Serve or refrigerate.

Tips

• Simplify: If preparing the mascarpone cream and ganache seems like too much work, you can simplify these eclairs further. Make the blueberry sauce, cut the eclairs in half horizontally, and fill the bottoms with the sauce. Then, pipe a nice layer of whipped cream before replacing the tops. You can even use aerosol whipped cream to make it even easier.

• Prep in advance: You can make the blueberry mascarpone cream and ganache in advance. Prep everything the day before and refrigerate it, sealed tightly. The next day, after you take the eclairs out of the oven, reheat the ganache in a double boiler until it’s thin enough to use as a topping, stirring often. Proceed with the final step as usual.

Storage

You can store these eclairs in the fridge for 3 to 4 days. Make sure the container is sealed tightly so they don’t absorb any smells. Note that they are best right after preparation, as they lose their crispness over time due to the moisture in the cream and ganache.

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