Heat oven to 350. Spray 13x8 pan with cooking spray. Whisk flour, baking powder & soda, and salt in medium bowl.
Beat 3/4 c butter and sugar in large bowl at medium speed 4 minutes or until light and fluffy. Beat in 1 Tbs lemon peel. Add eggs one at a time, beating well after each addition. Combine milk, lemon juice and vanilla in small bowl. At low speed, beat in flour mixture in 3 parts alternately with milk mixture just until blended, beginning and ending with flour mixture.
Spread batter in pan. Bake 35-40 minutes or until deep golden brown and toothpick inserted in center comes out clean. Cool completely on wire rack.
Beat cream cheese, 1/2 cup butter, lemon curd and 2 Tbs lemon peel at medium speed 2 minutes or until smooth. Slowly add powdered sugar; beat 2 minutes or until light and fluffy. Spread frosting over cake. Cover and refrigerate. Serve at room temperature. Store in refrigerator.