While a chocolate cupcake is special, a chocolate-filled cupcake is even better. You can fill the cupcakes before you bake them, or you can add the filling after the cupcakes are baked. A simple chocolate cream cheese filling makes the cupcakes an adult treat with the richness of cheesecake. If you add the filling after the cupcakes bake, use a little extra filling as frosting to hide the hole in the top of the cupcake.
Put the chocolate in a microwave-safe bowl. Microwave it on medium for 15-second intervals until it is completely melted. Stir it a little after each 15 seconds in the microwave. Make sure no water or other liquid gets into the chocolate at this stage, as that would make it seize.
Combine 1/2 cup cream, 1/2 cup powdered sugar, 8 ounces soft cream cheese and 1/4 teaspoon pure vanilla extract in a small mixing bowl. Beat the mixture until it is well-combined.
Stir the melted chocolate into the cream cheese mixture until it is well combined. Chill the mixture while you make the cupcake batter.
Preheat the oven to 350 degrees F. Spray the cupcake pan with baking spray.
Combine 1 1/2 cups of flour, 1 cup of sugar, 1/2 cup of cocoa powder, 1 teaspoon of baking soda and 1/2 teaspoon of salt in a large mixing bowl. Stir until all the dry ingredients are well-combined.
Combine 1/2 cup of melted butter, 1/2 cup of buttermilk, 1 teaspoon of vanilla extract and 1/2 cup of hot water in another bowl. The hot water keeps the butter from solidifying when it comes in contact with the buttermilk.
Pour the wet ingredients into the dry ingredients and stir to combine them. Don't over-mix -- a few lumps is all right. Divide the batter between the cupcake molds in the cupcake pan.
Scoop a rounded teaspoonful of the filling into the center of each cupcake. It will be covered with batter while it bakes. Quickly put the cupcakes into the oven to bake.
Bake the cupcakes for 20 to 25 minutes, until the top springs back when you press it lightly with your fingertip. You can also test with a toothpick; push the toothpick into the cupcakes about 1/2-inch from the edge, to avoid the filling. When the toothpick comes out clean or with one or two crumbs, the cupcakes are done.
Rest the cupcakes for 10 minutes and then turn them out of the cupcake pan. Let them cool on a rack before frosting them. Thin any remaining filling with a little hot water and glaze the cupcakes or make your favorite frosting.
Filling After Baking
Make and bake the cupcakes as instructed above, omitting the filling. Allow the cupcakes to cool before filling them.
Make the filling as directed above, after the cupcakes have cooked and cooled. Don't chill the filling -- keep it soft.
Cut a little slice off the top of each cupcake, reserving the pieces you cut off. Put the filling into a pastry bag fitted with a plain tip. Insert the tip into each cupcake and pipe in about 1 teaspoonful of filling. Pipe a little ring of filling on the cut surface of the cupcake to glue down the top. Replace the tops that were sliced off. Pipe a decorative design to hide the edges.
Use one tablespoonful of brewed coffee instead of vanilla in the cake and the filling. Coffee intensifies the chocolate flavor. Use oil instead of melted butter in the cake recipe. Choose a light-flavored oil such as canola or grape seed oil.