Prepare your cupcake casings.
Preheat oven to 170°Celsius.
Beat butter and both sugars till light and fluffy. Add eggs, one at a time, beating well after each addition.
Sift the flour, cocoa powder, baking powder and salt. Fold in the sifted ingredients into the creamed mixture alternately with milk, starting and ending with flour.
Add in the vanilla essence and mix well.
Pour batter into baking cups until they are about two thirds full. Sprinkle about 1/2 teaspoon for chocolate sprinkles on top of the cupcakes batter.
Bake the chocolate cupcakes for 15 to 20 minutes (depending on the size of the casing you use) or until a toothpick inserted in the center of the cupcakes comes out without any wet batter sticking to it.
Remove the cupcakes from oven and let them cool completely before decorating.
To make the buttercream, cream the butter until soft and creamy. Add the powdered sugar and beat until the buttercream is light and fluffy.
Sift in the cocoa powder and beat until it is well blended into the buttercream. Add milk if the buttercream is too stiff.
Fit a piping bag with a large star tip and pipe chocolate buttercream stars all over the top of each cupcake. Add chocolate sprinkles to each cupcake, followed by the white and gold sprinkles as preferred.