Gather and prep all ingredients: chop the onion and mince the garlic.
Heat a large skillet over medium heat. Add ground beef, diced onion, and minced garlic. Cook until browned, about 5 to 7 minutes. Drain excess fat.
Stir in tomato sauce, diced tomatoes, Italian seasoning, salt, and black pepper. Simmer for 5 minutes. Add uncooked elbow macaroni and beef broth, stir to combine, and bring to a boil.
Reduce heat to low, cover, and simmer for 10 minutes. Transfer to a greased 9x13-inch baking dish. Sprinkle mozzarella and Parmesan cheese on top. Bake in preheated oven for 20-25 minutes until cheese is bubbly and golden brown.
Let cool for a few minutes before serving.