Cream the butter with the sugar until fluffy. Add the eggs one at a time. Sift the flour, baking powder, and salt into the batter. Make a paste of the cocoa powder and milk and stir into the batter. Finally, fold in the chopped Easter eggs.
Place the cupcake liners in the muffin tin. Divide the cupcake batter between the papers. Bake in a preheated oven for 20 minutes. The cupcake is done when a skewer comes out clean and dry. Allow the cupcakes to cool.
To make the ganache, heat the heavy cream in a saucepan over low heat. Remove from the heat and add the white chocolate, stirring until well blended. Add the butter cubes at a time. Allow the ganache to set in the refrigerator. Beat the ganache with a mixer for 5 minutes until fluffy. Pipe the mixture into a pastry bag and pipe a nice bundle on each cupcake and garnish with the chopped Easter eggs.