Preheat oven to 350 degrees .
Grease two six inch round cake pans and line bottoms with parchment or wax paper. Grease again.
In a small bowl, whisk or just thoroughly together flour, baking powder, baking soda and salt; set aside.
In a medium bowl, beat the 1/4 cup room-temperature butter with an electric mixer on medium to high speed for 30 seconds. Beat in granulated sugar, 1/2 teaspoon vanilla and 1/2 teaspoon almond extract. Add egg whites, one at a time, beating well. Alternately add flour mixture and buttermilk, beating on low speed after each addition just until combined. Stir in sprinkles if using.
Divide batter between the two pans and bake for 22-25 minutes or until a toothpick inserted near center comes out clean.
Let the cakes cool in pans on wire rack for 10 minutes. Run knife around cake to loosen. Remove cake from pan; gently peel off paper. Cool completely on wire rack. If using one pan, wipe it clean and bake second layer with remaining batter.
For frosting: In a medium bowl, beat butter with an electric mixer on medium speed until smooth. Gradually add powdered sugar, 1/2 cup at a time, stirring until blended. Add a little of the milk and stir some more, then beat until smooth and creamy. Beat in a pinch of salt and the flavorings.
To assemble, place one cake layer, bottom side up, on a platter. Spread with 1/4 cup of frosting. Top with second layer, rounded side up. Spread top and sides with remaining frosting.