Preheat oven to 350 F. Line a 12 cup muffin pan with cupcake liners. In a large bowl, whisk flour, sugar, cocoa powder, salt, and baking powder together. Add in milk, oil, eggs, and vanilla extract, whisk until smooth.
Evenly divide cupcake batter between cupcake liners. Bake for 18-20 minutes. Let cool completely. Beat all of the chocolate frosting ingredients together until smooth. Place sprinkles in a shallow dish.
Frost cupcakes. Dip the tops of cupcakes in the sprinkles. Place two m&ms at the top for eyes and 2 Oreo cookie halves at the sides.