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

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

3. Remove the pan from heat and quickly stir in the flour until a dough ball forms and pulls away from the sides.

4. Let the dough cool for 5–7 minutes, then beat in eggs one at a time until fully incorporated and glossy.

5. Transfer the dough to a piping bag fitted with a large round tip. Pipe small mounds (about golf-ball size) onto the baking sheet.

6. Smooth the tops with a wet fingertip to avoid burnt peaks.

7. Bake for 20–25 minutes until puffed and golden brown. Do not open the oven door during baking.

8. Remove from oven and poke a hole in each puff to let out steam. Cool completely on a wire rack.

9. Whip the heavy cream with powdered sugar and vanilla until soft peaks form. Fold in mascarpone if using.

10. Fill each puff with cream using a piping bag, either slicing the tops off or filling through the steam hole.

11. Dust the tops with powdered sugar and serve immediately or refrigerate for up to 4 hours.