For the Cake:
Preheat oven to 350°F (180°C). Butter and flour two 9-inch round cake pans with 1 1/2-inch-high sides; line bottoms with rounds of parchment paper.
Sift first 3 ingredients into medium bowl. Beat butter in large bowl until fluffy. Gradually add sugar, beating until blended. Beat in concentrate, peel, and vanilla. Beat in eggs 1 at a time. Beat in flour mixture in 4 additions alternately with milk in 3 additions. Divide batter between prepared pans. Bake cakes until tester inserted into center comes out clean, about 30 minutes. Cool in pans on rack.
For the Filling:
Combine berries, sugar, and lemon juice in heavy small saucepan. Bring to boil over high heat, stirring until sugar dissolves. Boil until mixture is reduced to 3/4 cup, stirring occasionally and mashing berries coarsely with fork, about 8 minutes. Chill filling uncovered until cold, about 30 minutes.
For the Frosting:
Beat cream cheese and butter in bowl to blend. Beat in powdered sugar in 4 additions, then orange concentrate, peel, and vanilla. Chill until firm but spreadable, about 30 minutes.
To Assemble Cake:
Cut around cakes to loosen. Turn cakes out. Peel off parchment. Place 1 layer, flat side up, on platter. Spread filling to within 1/2 inch of edges. Chill 5 minutes. Top with second layer, flat side down. Spread 1/2 cup frosting thinly all over cake to seal. Spread remaining frosting over cake. If desired, spread blueberries over top of cake and garnish with strips of orange peel. (Can be made 1 day ahead; chill. Serve at room temperature.)
Makes 10 to 12 servings.
Date: May 13, 2004