Preheat oven to 375 degrees F. Grease and flour two 8-inch round cake pans.
Prepare, bake and cool cake according to package directions.
Beat whipping cream in a large bowl until soft peaks form. Add sugar gradually.
To assemble, place one cake layer on serving plate. Spread two-thirds cherry pie filling on cake to within 1/2-inch of edge. Spread 1.5 cups whipped cream mixture over cherry pie filling. Top with second cake layer. Frost sides and top with remaining whipped cream mixture. Spread remaining cherry pie filling on top to within 1-inch of edge. Refrigerate until ready to serve.