Oven Preheat: Set oven to 390°F (200°C).
Boil Mixture: Boil butter, milk, water, salt, and sugar.
¼ cup water, ¼ cup milk, 3 tbsp unsalted butter, ¼ tsp salt, 1¼ tsp sugar
Add Flour: Off heat, add flour and stir; return to heat for 2-3 minutes constantly stirring until glossy.
2½ oz all-purpose flour
Cool Dough: Transfer to a bowl; cool for 10 minutes.
Whisk Eggs: In a separate bowl, whisk eggs.
2 large eggs
Mix Dough: Add eggs to dough gradually, aiming for a thick, pipeable consistency. Make sure the dough passes the V-shape test.
Prep Tray: Line a baking tray with parchment or silicone mat.
Pipe Dough: Fill a piping bag; pipe dough into 12 to 16 mounds on the tray.
Baking: Bake at 356°F (180°C) for 40 minutes; open oven door slightly in the last 5 minutes.
Cool Puffs: Let puffs cool for 10-15 minutes, then carefully detach from the parchment paper and cool on a wire rack for another 10 to 15 minutes.