Preheat your oven to 425°F (220°C).

In a medium saucepan over medium heat, combine 1 cup of water and 1/2 cup of butter. Stir until the buttermelts completely and comes to a rolling boil.

Add 1 cup of all-purpose flour all at once, stirring vigorously until a smooth dough forms. Continue to cook for about 1-2 minutes until it pulls away from the sides of the pan.

Remove from heat, allow cooling for about 5 minutes, then add 4 large eggs one at a time, mixing well after each addition.

Pipe the dough onto a parchment-lined baking sheet, leaving about 2 inches between each mound.

Bake for 20-25 minutes, until golden brown and puffed up. Do not open the oven door during the first 20 minutes.

While baking, whip 1 cup of heavy cream with 1 teaspoon of vanilla extract and 2 tablespoons of sugar until stiff peaks form.

Once baked and cooled, gently slice each puff in half and fill with whipped cream mixture.