Preheat the oven to 375 degrees F. Coat a 10-inch Bundt or tube pan with nonstick cooking spray. In a large bowl, combine the ground beef, onion, bread crumbs, 1 cup ketchup, the eggs, salt, and pepper; mix well. Place in the prepared pan. Spread the remaining 1/2 cup ketchup over the top of the meat. Bake for 1 to 1 1/2 hours, or until the juices run clear; drain off any liquid. Allow to sit for 5 minutes, then remove to a serving platter. "Frost" the meat with the mashed potatoes and garnish the bottom edge with the cherry tomato halves. NOTE: Feel free to decorate this "cake" any way like. Sometimes I drizzle beef gravy over the mashed potato frosting to look like chocolate glaze. Happy April Fools Day! NOTES : 6 to 8 servings