In a medium bowl, stir together the 2 cups flour, baking powder, baking soda, salt, and nutmeg. In a large bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Add the granulated sugar and vanilla. Beat until combined, scraping side of bowl occasionally. Add eggs one at a time, beating after each addition. Alternately add flour mixture and sour cream to butter mixture, beating on low speed after each addition just until combined (batter will be stiff).