Ingredients:
130 g (about 1 cup) all-purpose flour
50 g (about 3.5 tablespoons) unsalted butter
150 g (about 3/4 cup) packed brown sugar
25 g (about 1/4 cup) cocoa powder
50 g (about 1.75 oz) dark chocolate
1 large egg
1/4 teaspoon baking powder
a pinch of salt
Melt the butter in a saucepan over medium heat, then add the sugar, cocoa powder, a pinch of salt, and the dark chocolate. Stir until the sugar and chocolate are fully dissolved. Remove from heat, add the egg, and mix well. Gradually incorporate the sifted flour and baking powder until the mixture is smooth. Chill the dough in the refrigerator for 30 minutes to 1 hour.
Using a spoon, drop the dough onto a silicone mat or parchment paper, forming balls spaced about 2-3 cm apart. Bake at 180°C (350°F) for 10-12 minutes. Store the cookies in an airtight container.