Lemon Cake Roll

PreparationMake filling: Combine sugar and cornstarch in heavy medium saucepan. Whisk in 1 1/4 cups buttermilk and lemon juice. Whisk in egg yolk. Simmer mixture over medium heat until thick, stirring constantly, about 1 minute. Stir in butter, lemon peel and food coloring. Remove from heat. Transfer to medium bowl. Whisk in 2 tablespoons buttermilk. cover surface of filling with plastic wrap; cool to room temperature. (Can be made 1 day ahead. Chill.) Make cake: Preheat oven to 375°F. Spray 13 1/4 x 9 1/4 x 3/8-inch jelly roll pan with vegetable oil spray. Line pan with waxed paper and spray paper. Lightly coat paper with flour; tap out excess. Combine flour and baking powder in medium bowl. combine eggs and egg whites in large metal bowl. Set bowl over saucepan of simmering water (do not allow bowl to touch water). Whisk eggs until just warm to touch, about 2 minutes. Remove bowl from over water. Add sugar and salt. Using electric mixer, beat egg mixture until fluffy, thick and pale, about 6 minutes. Sift flour mixture atop egg mixture; gently fold in. Fold in butter (do not overmix or batter will deflate). Transfer batter to prepared pan. Tilt pan to coat thinly. Bake until top springs back when touched and edges are light golden, about 12 minutes. Sift powdered sugar over hot cake. Place 2 paper towels over cake. Place rimless baking sheet atop cake and invert cake onto baking sheet. Remove waxed paper. Trim edges of cake to form 13 x 8-inch rectangle. Starting at 1 short end of cake, roll up jelly roll style, discarding paper towels. Cool completely. Unroll cake. Whisk filling to smooth. Spread filling evenly over surface of cake. Starting at 1 short end of cake re-roll cake jelly roll style. Transfer cake, seam side down to platter. Cover with plastic wrap and refrigerate 2 hours. (Can be prepared 1 day ahead. Keep chilled.) Cut cake into eight 1-inch slices. Garnish with lemon slices and mint sprigs, if desired.

PreparationMake filling: Combine sugar and cornstarch in heavy medium saucepan. Whisk in 1 1/4 cups buttermilk and lemon juice. Whisk in egg yolk. Simmer mixture over medium heat until thick, stirring constantly, about 1 minute. Stir in butter, lemon peel and food coloring. Remove from heat. Transfer to medium bowl. Whisk in 2 tablespoons buttermilk. cover surface of filling with plastic wrap; cool to room temperature. (Can be made 1 day ahead. Chill.) Make cake: Preheat oven to 375°F. Spray 13 1/4 x 9 1/4 x 3/8-inch jelly roll pan with vegetable oil spray. Line pan with waxed paper and spray paper. Lightly coat paper with flour; tap out excess. Combine flour and baking powder in medium bowl. combine eggs and egg whites in large metal bowl. Set bowl over saucepan of simmering water (do not allow bowl to touch water). Whisk eggs until just warm to touch, about 2 minutes. Remove bowl from over water. Add sugar and salt. Using electric mixer, beat egg mixture until fluffy, thick and pale, about 6 minutes. Sift flour mixture atop egg mixture; gently fold in. Fold in butter (do not overmix or batter will deflate). Transfer batter to prepared pan. Tilt pan to coat thinly. Bake until top springs back when touched and edges are light golden, about 12 minutes. Sift powdered sugar over hot cake. Place 2 paper towels over cake. Place rimless baking sheet atop cake and invert cake onto baking sheet. Remove waxed paper. Trim edges of cake to form 13 x 8-inch rectangle. Starting at 1 short end of cake, roll up jelly roll style, discarding paper towels. Cool completely. Unroll cake. Whisk filling to smooth. Spread filling evenly over surface of cake. Starting at 1 short end of cake re-roll cake jelly roll style. Transfer cake, seam side down to platter. Cover with plastic wrap and refrigerate 2 hours. (Can be prepared 1 day ahead. Keep chilled.) Cut cake into eight 1-inch slices. Garnish with lemon slices and mint sprigs, if desired.