1. Heat Ingredients: In a medium saucepan, combine the water (or milk), butter, and sugar (if using). Melt the butter and bring the mixture to a boil over medium heat.

2. Add Flour: Remove the saucepan from heat and quickly add the sifted flour and salt all at once. Using a wooden spoon, stir until the dough becomes smooth. It should pull away from the sides of the pan.

3. Cool the Dough: Let the dough cool for about 10 minutes. This is important because if it’s too hot when you add the eggs, they will cook instead of mixing in.

4. Add Eggs: One by one, add the eggs, thoroughly mixing each time. The batter should be smooth and shiny. If it seems too thick, you can add another egg.

1. Preheat Oven: Preheat your oven to 220°C (428°F).

2. Pipe the Dough: Put the choux pastry into a piping bag with a round tip. Pipe small mounds on baking sheets lined with parchment paper, leaving space between them.

3. Bake: Bake for about 15-20 minutes until they are golden brown and puffed up. Do not open the oven door while they bake.

4. Cool Down: Once baked, take them out and pierce each one with a skewer to let steam escape. This helps keep them crisp. Let them cool on a wire rack.

1. Prepare Filling: If using whipped cream, beat it until it holds soft peaks.

2. Fill Profiteroles: Once cooled, cut each profiterole in half and fill with whipped cream or your choice of filling.

3. Make Chocolate Sauce: Heat heavy cream in a small saucepan until it simmers. Remove from heat and stir in chopped chocolate until smooth.

4. Serve: Drizzle warm chocolate sauce over filled profiteroles before serving.