Using a stand mixer with a paddle, mix the almond paste. Gradually add the eggs one at a time. Add the cocoa powder and mix until combined. Warm the melted butter and add it to the mixture until completely combined. Butter and flour mini muffin tins or flexipan molds, however, if you prefer, you can use paper liners for the muffin tin. Fill each cavity 1/8-inch from the top. Bake for 8 minutes being careful not to overbake or they will be too dry.