Boil Milk Mixture: In a pot, whisk together milk, pumpkin puree, vanilla extract, pumpkin pie spice, and sugar. Bring to a boil, stirring occasionally.
1 cup milk, 1/2 cup pumpkin puree, 1 teaspoon pumpkin pie spice, 1 teaspoon vanilla extract, 7 tablespoons brown sugar
Prep Yolks: Whisk egg yolks in a large bowl and stir in cornstarch. Add a couple of teaspoons of the milk mixture to thin things out.
2 egg yolks, 3 tablespoons cornstarch
Temper Eggs: Gradually pour hot milk mixture into the yolks, whisking constantly, until fully combined.
Cook Until Thick: Return the mixture to the pot and cook over medium heat, stirring, until it thickens and starts to bubble.
Whisk Off Heat: Remove from heat and whisk for about a minute off heat.
Stir in Butter: Add butter and stir until melted.
2 tbsp unsalted butter
Taste and Adjust: Add sugar or pumpkin pie spice if needed.
Strain (Optional): Strain through a mesh strainer for a smoother texture.
Cover and Chill: Cover with plastic wrap and cool at room temperature, then refrigerate.
Whisk and Use: Whisk chilled cream until smooth before using.