Cook spaghetti according to package instructions. (Drain but don’t rinse)
While spaghetti is cooking slice bacon into 1-inch pieces. Cook in a frying pan until crispy. Drain on paper towels reserving 3 teaspoons of bacon grease. In a medium-size saucepan cook the tomatoes until hot.
In a large frying pan cook the ground beef and onion until ground beef is no longer pink inside. Drain if needed
In a 2-quart casserole dish sprayed with cooking spray mix together the burger, tomatoes, bacon pieces, and bacon grease. Salt and pepper to taste, mix in 1/2 the cheese, and then fold in the spaghetti. Top with the remaining cheese.