Preheat your oven to 375 degrees Fahrenheit.
Line a cupcake pan with paper baking cups.
Gather your ingredients.
Add the butter, sugar, egg, flour, and cocoa powder to a large bowl.
Mix it all together to form a thick batter.
Full your cupcake liners halfway with batter.
Use a teaspoon to make an indention in the middle of the batter. Evenly divide the chocolate amongst the cupcakes.
Cover the chocolate with the remaining batter. Bake the cupcakes for 15-20 minutes, or until they have significantly risen and feel spongy to the touch.
Once the cupcakes are done baking, let them sit for about three minutes to cool down a bit.
Dust with confectioners sugar.