Step 1: Preheat the Oven

1. Preheat your oven to 400°F (200°C).
2. Line a baking sheet with parchment paper or a silicone baking mat.

Step 2: Make the Choux Pastry

1. In a medium saucepan, combine butter, water, sugar, and salt over medium heat.
2. Stir until the butter is fully melted, then bring the mixture to a rolling boil.
3. Reduce the heat to low and add the flour all at once, stirring vigorously with a wooden spoon.
4. Continue stirring for about 1-2 minutes, until the dough pulls away from the sides of the pan and forms a ball.

Step 3: Incorporate the Eggs

1. Remove the pan from heat and let the dough cool for 5 minutes.
2. Add the eggs one at a time, mixing well after each addition. The dough may look separated at first but will come together into a smooth, glossy batter.
3. Transfer the choux pastry into a piping bag fitted with a large round tip.

Step 4: Pipe and Bake

1. Pipe 1 ½-inch mounds of dough onto the prepared baking sheet, spacing them about 2 inches apart.
2. Lightly wet your finger and smooth down any peaks to prevent burning.
3. Bake for 25-30 minutes, or until the puffs are golden brown and crisp.
4. Turn off the oven and let the puffs rest inside with the door slightly open for 10 minutes to prevent collapsing.

Step 5: Prepare the Filling

1. In a mixing bowl, beat heavy cream, powdered sugar, and vanilla extract until stiff peaks form.
2. Transfer the whipped cream to a piping bag fitted with a small round or star tip.

Step 6: Fill the Cream Puffs

1. Once the pastry shells are completely cool, use a sharp knife to cut a small slit in the bottom or slice them in half.
2. Pipe the vanilla cream into the center of each puff.
3. Dust with powdered sugar or drizzle with melted chocolate before serving.