Grease and flour three 9-in. round baking pans; set aside. , In a large bowl, cream butter and sugar until light and fluffy. Add egg whites, one at a time, beating well after each addition. Beat in the strawberries, sour cream and extract. Combine the flour, baking powder, baking soda and salt; add to the creamed mixture. Transfer batter to prepared pans. , Bake at 350° until a toothpick inserted in the center comes out clean, 22-26 minutes. Cool for 10 minutes before removing from pans to wire racks to cool completely., For frosting, in a large bowl, beat cream cheese and butter until fluffy. Add the confectioners’ sugar, strawberries, extract and, if desired, food coloring; beat until smooth. , Place bottom cake layer on a serving plate; top with 1/2 cup jam and 1/2 cup frosting. Repeat layers. Top with remaining cake layer. Spread remaining frosting over top and sides of cake. Garnish with sliced strawberries if desired.