Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a medium saucepan, combine the water, milk, unsalted butter, sugar, and salt over medium heat until rolling boil.

Remove from heat and add all-purpose flour, stirring until a smooth dough forms.

Transfer dough to a mixing bowl and let cool for about 5 minutes.

Add eggs one at a time, mixing well after each addition until smooth and glossy.

Using a piping bag or spoon, place mounds of dough 2 inches wide on prepared baking sheet.

Bake for 15 minutes at 400°F, then reduce to 350°F and bake for an additional 20-25 minutes until golden brown.

Poke a small hole in each puff to release steam and allow cooling on a wire rack.

Whip heavy cream, powdered sugar, and vanilla in a chilled mixing bowl until stiff peaks form.

Slice the tops off each puff, fill with Chantilly cream, replace tops, and dust with powdered sugar before serving.