This Cheesy Ground Beef and Rice Casserole is a hearty one-pot meal perfect for a comforting dinner. Ground beef is browned and simmered with onions, garlic, mushrooms, and rice in beef broth, then combined with creamy mushroom soup, sour cream, and plenty of cheddar cheese. The mixture is baked until bubbly and golden, creating a deliciously cheesy, savory casserole that serves six.