Cupcakes:

Preheat to 350° F. Line muffin pans with paper baking cups. In a large bowl, whisk flour, ground almonds, baking powder and salt. In a separate bowl, cream butter and sugar until smooth. Add egg yolks and beat well; beat in almond extract. Gradually add flour mixture, alternating with milk, beginning and ending with flour mixture. Mix until just blended. In a clean bowl with clean beaters, beat egg whites until stiff peaks form. Gently fold in egg whites into batter with a spatula. Divide batter evenly among the pan, filling each about 3/4-full. Bake 18-22 minutes or until a toothpick inserted in center comes out clean. Cool on wire rack before frosting.

Frosting:

With an electric mixer, combine sugar, butter, milk and vanilla. Beat at medium speed for 1-2 minutes until creamy. If desired, add more milk until frosting is spreading consistency. Pipe frosting onto cupcakes using a piping bag without a tip.