To make cupcakes of the same size, use a solid plastic ice cream scoop to measure out the batter and fill the muffin cups.
Batter for a two-layer 9-in. cake can be used to make 2 to 2-1/2 dozen cupcakes. Fill greased or paper-lined muffin cups two-thirds full. Bake at 350° for 20 to 30 minutes before removing from pans to wire racks to cool completely. Frost as desired.