Preheat your oven to 350°F (175°C).
In a skillet, cook the ground beef over medium heat until browned.
Drain excess fat and add chopped onions; sauté until translucent.
Stir in diced tomatoes, ketchup, mustard, and seasonings.
Mix in the cooked pasta until well combined.
Spread half of the meat mixture in a greased casserole dish.
Layer half of the shredded cheese on top.
Repeat with remaining meat mixture and cheese.
Top with slices of bread for added crunch.
Bake for 25-30 minutes until the cheese is melted and bubbly.