1/2 cup cake flour (about 2 ounces)
3/4 cup powdered sugar
3/4 cup egg whites (about 5 large eggs)
1/8 teaspoon salt
3/4 teaspoon cream of tartar
1/2 cup granulated sugar
1/2 teaspoon vanilla extract
2 teaspoons grated lemon rind
1/4 cup butter, softened
2 cups powdered sugar
1 tablespoon 1% low-fat milk
1 to 2 tablespoons freshly squeezed lemon juice
Edible flowers such as pansies or rosebuds (optional)
Preheat oven to 350°.
Place 16 paper muffin cup liners in muffin cups. Set aside.
Lightly spoon cake flour into dry measuring cups; level with a knife. Sift together flour and 3/4 cup powdered sugar into a medium bowl; repeat the procedure 2 times.
Beat egg whites and salt with a mixer at high speed until frothy (about 1 minute). Add cream of tartar, and beat until soft peaks form. Add 1/2 cup granulated sugar, 1 tablespoon at a time, beating until stiff peaks form. Sprinkle flour mixture over egg white mixture, 1/4 cup at a time; fold in after each addition. Stir in vanilla and rind.
Divide batter evenly among prepared muffin cups. Bake at 350° for 18 minutes or until lightly browned. Remove from pan; let cool completely on a wire rack.
To prepare frosting, beat butter with a mixer at high speed until fluffy. Gradually add 2 cups powdered sugar; beat at low speed just until blended. Add milk and lemon juice; beat until fluffy. Add more lemon juice as needed to adjust the consistency. Spread 2 tablespoons lemon frosting over each cupcake. Garnish with edible pansies and rosebuds, if desired.