Preheat oven to 350°F (175°C).

In a large pot, brown the ground beef over medium-high heat. Season with Italian seasoning, salt, and pepper. Drain excess grease and set beef aside.

In the same pot, melt 2 Tbsp butter. Add onions and cook until softened, about 5 minutes. Add garlic and cook for 1 more minute.

Add beef broth, remaining butter, and rice. Bring to a boil, then reduce heat, cover, and simmer for 10 minutes.

Add mushrooms on top (don't stir), cover, and cook for another 5-10 minutes until rice is tender.

Remove from heat and let stand, covered, for 10 minutes.

Stir in the cooked beef, cream of mushroom soup, milk, sour cream, and half the cheese.

Transfer to a greased 9x13 casserole dish. Top with remaining cheese.

Cover and bake for 20 minutes until cheese is melted and bubbly.

Enjoy your homemade Beef and Rice Casserole!