Step 1

Preheat the oven to 425°F (220°C) and line two 8" round or square cake pans with parchment paper.

Step 2

In a pot over medium heat, combine water and butter, bringing it to a rapid boil.

Step 3

Stir in flour, salt, and baking powder with a wooden spoon until it forms a dough ball. Transfer to a mixing bowl.

Step 4

Add eggs one at a time, mixing well after each addition.

Step 5

Divide the batter into the prepared pans and pipe it in. Bake for 35 minutes or until golden brown. Remove from pans and cool completely on a rack.

Step 6

In a saucepan, heat milk and vanilla over medium heat until it boils.

Step 7

In a separate bowl, mix egg yolks, egg, sugar, salt, and cornstarch.

Step 8

Once milk boils, reduce heat to low. Whisk a spoonful of milk into the egg mixture quickly to temper the eggs.

Step 9

Gradually add the egg mixture to the pot with the milk, whisking until thickened.

Step 10

Pour the pastry cream into a bowl, cover, and chill completely in the fridge.

Step 11

Once cooled, fold in the whipped topping.

Step 12

Place one cake shell in an 8" baking dish.

Step 13

Lay the first cake layer on top and spread with pastry cream filling.

Step 14

Place the other cake shell on top (bottom side up for a flat surface).

Step 15

Cover, press down gently, and refrigerate for at least 2 hours to set.

Step 16

Dust the top with powdered sugar before serving.

Step 17

Optional: Serve with fresh berries.