Preheat oven to 375 degrees. Butter a 13" x 9" baking dish, set aside. In a mixing bowl combine flour, baking powder and salt, set aside. In the bowl of an electric mixer, whip together butter and sugar until pale and fluffy about 3-4 minutes. Stir in egg and egg white. Add sour cream, vanilla and almond extract and mix until blended. Slowly add dry mixture and stir until combined. With buttered hands, gently press (so gently almost patting) mixture into buttered baking dish. Bake 15 - 17 minutes until toothpick inserted into the center comes out clean and bars are set. Cool completely, then frost and cut into squares.
Vanilla Frosting
In a mixing bowl, with an electric mixer, whip together butter and powdered sugar and half and half until fluffy. Stir in vanilla. Add in food optional food coloring and mix until well blended.
*Recipe updated 4/5/15. Originally 8 Tbsp I've started making them with 10 and like them even more.