Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a medium saucepan, combine butter and 1 cup of water. Bring to a boil over medium heat.
Remove from heat and quickly stir in flour until the mixture forms a ball.
Transfer the dough to a large bowl and let cool for 5 minutes.
Add eggs, one at a time, beating well after each addition until the dough is smooth and glossy.
Spoon the dough onto the prepared baking sheet, forming small mounds.
Bake in the preheated oven for 20-25 minutes until golden and puffy.
Allow the profiteroles to cool completely on a wire rack.
Beat the heavy cream with sugar until stiff peaks form, then fill the profiteroles with the whipped cream.
For the chocolate sauce, heat the milk in a saucepan over low heat, then add the chopped chocolate, stirring until smooth.
Drizzle the chocolate sauce over the cream-filled profiteroles and serve.