Preheat oven to 350 degrees F. Line a large, rimmed baking with parchment paper and set aside. Combine all ingredients in a large mixing bowl. Mix well using a heavy spoon or your hands.
2 lbs ground beef, 1 cup Ritz crackers, 2 eggs, 1 cup milk, 1/2 cup ketchup, 1/2 cup onion, 1/4 cup Parmesan cheese, 1/4 cup Italian parsley, 1 tbsp Worcestershire sauce, 2 cloves garlic, 1/2 tsp salt, 1/2 tsp pepper