Preheat oven to 350°. Prepare cake mix according to package directions, baking in 8-inch baking pan. On wire rack, cool completely. Remove cake from pan; set aside. Clean same baking pan, then line with aluminum foil; set aside.
Cut cake horizontally in half. Place bottom half of cake in pan, cut-side-up, then top with Breyers All Natural Butter Pecan Ice Cream, pressing to form an even layer. Gently press on top half of cake, cut-side-down. Cover and freeze 4 hours or overnight. Lift cake from pan using foil; remove foil. Let stand 10 minutes before serving. Just before serving, sprinkle with confectioners sugar.