1. Preheat oven to 350°.
2. To prepare cake, place sliced strawberries in a food processor; process until smooth.
3. Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, and salt, stirring with a whisk. Place granulated sugar and 1/2 cup butter in a large bowl; beat with a mixer at medium speed until well blended. Add eggs, one at a time, beating well after each addition. Beat in egg whites. Add flour mixture and buttermilk alternately to sugar mixture, beginning and ending with flour mixture. Add pureed strawberries and food coloring; beat just until blended.
4. Divide batter between 2 (8-inch) round cake pans coated with cooking spray. Bake at 350° for 30 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on a wire rack for 10 minutes. Remove from pans; cool completely on wire racks.
5. To prepare frosting, place cream cheese, 1/3 cup butter, and liqueur in a medium bowl; beat with a mixer at medium speed until blended. Gradually add powdered sugar, and beat just until blended.
6. Place 1 cake layer on a plate; spread with 1/2 cup frosting. Top with remaining cake layer. Spread remaining frosting over top and sides of cake. Cut 1 whole strawberry into thin slices, cutting to, but not through, the stem end. Fan strawberry on top of cake just before serving, if desired. Cut remaining 11 strawberries in half. Garnish cake with strawberry halves, if desired.