Step 1

Begin by sifting the flour and setting it aside. In a saucepan, combine the butter, water, milk, salt, and sugar. Heat the mixture over medium heat, bringing it to a simmer, but avoid letting it come to a boil.

Step 2

Once the mixture is simmering, remove the saucepan from the heat and add the flour all at once. Stir vigorously with a rubber spatula until the dough is smooth, with no traces of flour remaining. Return the pan to the heat and cook for 3-5 minutes, stirring continuously, until a thin film forms at the bottom of the pan and some of the liquid evaporates.

Step 3

Transfer the dough into the bowl of a stand mixer. With the paddle attachment, mix on low speed for about a minute to allow it to cool slightly. Slowly incorporate the lightly beaten eggs, adding them gradually and ensuring each addition is fully blended before adding more. Continue mixing for 2-3 minutes until the dough becomes glossy and easily pipeable.

Step 4

The dough is ready when it falls from the paddle in a V shape and holds its form—it should not be runny. Since the amount of eggs needed can vary depending on the flour and moisture lost during cooking, adjust the quantity as necessary.

Step 5

Transfer the dough into a pastry bag fitted with a 0.5-inch French star tip. Refrigerate the dough for about 1 hour.

Step 6

After resting, pipe the dough into 12 evenly sized cream puffs onto a perforated baking mat (leaving space between each for expansion) or onto a parchment-lined baking sheet. Pipe at a 90° angle (keeping the piping bag straight vertically) and apply even pressure. Smooth any tips by gently tapping them with a damp finger.

Step 7

Lightly dust the profiteroles with powdered sugar to help prevent cracking. Freeze for at least one hour, or longer if you need the cream puffs later.

Step 8

Preheat the oven to 200°C / 392°F (without fan). Once the dough is frozen, place the tray in the oven, reduce the temperature to 170°C / 338°F (without fan), and bake for 40 minutes. Avoid opening the oven door during the first 30 minutes. If this is your first time baking, remove one choux bun after 40 minutes to check— it should be golden, puffed up, and should not deflate at room temperature.

Step 9

Let the cream puffs cool on the perforated mat at room temperature before filling them.

Step 10

Add very cold heavy cream and mascarpone to a mixing bowl along with the sifted powdered sugar.

Step 11

Use an electric hand mixer to whip the mixture for about a minute, then add the vanilla extract.

Step 12

Continue whipping for 2 to 3 minutes, or until the cream reaches a fluffy, pipeable consistency (after soft peaks but before stiff peaks). Be sure to stop whipping right away to avoid over-beating. If you continue, the chantilly cream will separate and become runny.

Step 13

Cut the tops off the cream puffs, then transfer the whipped cream into a piping bag fitted with a nozzle (I am using Wilton 1M piping nozzle tip). Pipe the cream into each puff, and finish by dusting with powdered sugar.

Step 14

Cream puffs are best enjoyed immediately after filling, as they lose their crispiness over time. Any leftovers can be stored in the fridge for up to a day.