Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.

In a saucepan, combine water, butter, sugar, and salt. Bring to a boil over medium heat.

Remove from heat and stir in flour until the mixture forms a ball.

Let cool slightly, then add eggs one at a time, mixing well after each addition.

Transfer the dough to a piping bag and pipe a large ring onto the prepared baking sheet.

Bake for 25 minutes or until golden brown and puffed. Let cool completely.

In a mixing bowl, whip the heavy cream until soft peaks form.

Gently fold in hazelnut paste, powdered sugar, and vanilla extract until well combined.

Cut the choux pastry ring in half horizontally.

Fill the bottom half with the hazelnut cream filling using a piping bag.

Replace the top half and garnish with chopped hazelnuts and a dusting of powdered sugar.