Preheat oven to 350 degrees F (175 degrees C). Grease and flour 24 muffin cups.
In a medium bowl, sift together flour, cocoa powder, baking soda, baking powder and salt. Set aside.
In a large bowl, cream butter and sugar until light and fluffy. Beat in eggs one at a time, then stir in the sour cream and vanilla. Beat in the flour mixture alternately with the milk; mix just until incorporated. Spoon batter into prepared cups.
Bake in preheated oven for 20 to 25 minutes, or until a toothpick inserted into the center of a cupcake comes out clean. Allow cupcakes to cool in the pans for 10 minutes, then remove to cool completely on a wire rack.
In a medium bowl, beat together the heavy cream and powdered sugar until stiff peaks form. Fill a pastry bag fitted with a large star tip with the cream. Pipe cream into each cupcake and serve.
Interesting Facts
Chocolate cupcakes date back to the 19th century.
Chocolate cupcakes were originally called "cup cakes" because the ingredients were measured in cups.
Cupcakes are a popular dessert in the United States.