In a medium saucepan, combine 1 cup of water, ½ cup of unsalted butter, 1 tablespoon of sugar, and ½ teaspoon of salt. Heat over medium until the butter melts completely and the mixture begins to bubble.

Once the mixture is bubbling, quickly stir in 1 cup of all-purpose flour. Mix vigorously with a wooden spoon until a smooth dough forms that pulls away from the sides of the pan, about 2-3 minutes.

Transfer the hot dough to a mixing bowl and let it cool for about five minutes. Stir occasionally to help release some heat; the dough should not be too hot when adding the eggs.

Beat in 4 large eggs, one at a time, using a hand mixer or a sturdy spoon. Ensure each egg is fully incorporated before adding the next.

Spoon or pipe tablespoon-sized mounds of dough onto a lined baking tray, leaving space between each.

Bake the profiteroles in your preheated oven at 425°F (220°C) for 20-25 minutes until they are golden brown.

Once out of the oven, pierce each profiterole with a sharp knife to let steam escape. Place them on a wire rack to cool completely.

In a mixing bowl, whip together 1 cup of heavy cream, ¼ cup of powdered sugar, and 1 teaspoon of vanilla extract until stiff peaks form.

Once your profiteroles are completely cool, fill each puff generously with the whipped cream.

In a small saucepan, warm ½ cup of heavy cream over low heat; do not boil. Remove from heat and add ½ cup of semisweet chocolate, stirring until melted and smooth.

Drizzle the warm chocolate sauce over your filled profiteroles, allowing it to cascade down the sides.