Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Start by making the craquelin. In a bowl, cream together the softened butter and granulated sugar until light and fluffy. Gradually add the flour and mix until well combined. Roll the dough between two sheets of parchment paper until it’s about 1/8 inch thick. Place the rolled craquelin in the freezer to firm up.
To prepare the choux pastry, in a saucepan, combine the water, butter, and salt. Bring it to a boil over medium heat. Once the butter has melted completely and the mixture is boiling, remove the saucepan from the heat.
Add the flour all at once to the saucepan and stir vigorously until a smooth dough forms. Return the saucepan to low heat and continue stirring for about 2 minutes to cook the dough slightly.
Transfer the dough to a mixing bowl and let it cool for a few minutes. Beat in the eggs, one at a time, until fully incorporated. The dough should be smooth and glossy.
Transfer the choux pastry dough to a piping bag fitted with a large round tip. Pipe small mounds onto the prepared baking sheet, leaving space between them for expansion. Take the craquelin out of the freezer and cut out small circles slightly larger than the choux mounds. Place a craquelin circle on top of each choux mound.
Bake in the preheated oven for 25-30 minutes, or until the choux puffs are golden brown and crispy. Avoid opening the oven door while they’re baking, as it can cause them to deflate.
Once the choux puffs are baked, remove them from the oven and transfer them to a wire rack to cool completely.
While the choux puffs are cooling, prepare the vanilla whipped ganache. In a mixing bowl, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
To assemble, use a sharp knife or a pastry bag with a small tip to make a small hole in the bottom of each choux puff. Fill the puffs with your desired filling, such as pastry cream or flavored cream.
Finally, pipe or spoon the vanilla whipped ganache on top of each filled choux puff. You can also dip the top of each puff in melted chocolate for added flavor and decoration.
