You could serve the filling on toasted English muffins or bagels if youʼd like too.
Hands-on: 20 minutes
Total: 30 minutes
¾ lb. lean ground beef
1 medium onion, peeled and chopped
1 Tbsp. all-purpose flour
2 cups marinara sauce
½ cup grated carrots
½ tsp. dried Italian seasoning
½ tsp. garlic salt
¼ cup grated Parmesan cheese
1½ cups shredded mozzarella cheese, divided
4 hamburger buns, cut in half
2 Tbsp. butter, softened
In a large saucepan, cook ground beef and onion together over medium heat, stirring occasionally, until meat is browned and cooked. Drain off excess fat and water.
Sprinkle flour over meat; cook and stir for 1 minute. Then add marinara, carrots, Italian seasoning, and salt. Bring to a boil, reduce heat, and simmer for about 5–8 minutes until thickened. Stir in Parmesan cheese and ½ cup mozzarella cheese; remove from heat.
Preheat broiler. Spread cut sides of hamburger buns with butter and toast under broiler. Remove from oven and divide beef mixture among buns. Top with remaining mozzarella cheese. Broil 6″ from heat for 4–5 minutes or until sandwiches are hot and cheese is melted and bubbly. Serve immediately.