1. Combine ground beef, onion, eggs, bread crumbs, ketchup, salt, and pepper; shape into into twelve thin (about 1/4-inch thick) patties. 2. Melt the butter in a skillet and sauté the mushrooms until just tender. 3. Place mushrooms on 6 of the patties. Top with remaining patties and seal edges. 4. Broil or grill the burgers to desired doneness. 5. Top each burger with a slice of cheese and let it melt. Serve on split toasted buns. Enjoy! ---------------------------------------------------------------------------
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Ingredients