Preheat the oven to 180°C.
Sieve flour, cocoa powder and baking powder in a bowl. Mix well.
Mix softened butter with sugar.
Beat the egg, and gradually add it to the butter-sugar mixture. Mix well after each addition.
In a double boiler, melt the chocolate together with milk.
Add flour mixture and melted chocolate little by little to the butter mix, mix well after each addition.
Break the Oreo into smaller pieces. Add oreo chunks to the mix.
Put the mixture evenly to 6 muffin tins.
Bake in the oven for 12-15 mins until skewer comes out clean.