In a large bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Add the 1 cup sugar, the baking powder, nutmeg, and baking soda; beat until combined. Beat in sour cream, egg product, and vanilla until combined. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour. Cover and chill for 1 to 2 hours or until dough is easy to handle.