1-First, start by preheating your oven to 350°F (175°C). This step ensures even cooking and helps meld the flavors together. Dice the onions and measure out all ingredients to make the process smooth and efficient.

2-In a large pot over medium-high heat, brown the ground beef until it’s fully cooked, seasoning it with salt, pepper, and Italian seasoning. Drain any excess grease and set the beef aside, covering it with foil to keep it warm. This adds a hearty base to your casserole.

3-Next, melt 2 tablespoons of butter in the same pot and add the diced onions, cooking them until softened, about 5 minutes. Then, stir in the minced garlic and cook for another minute to release its aroma. This builds a flavorful foundation for the dish.

4-Now, add the beef broth, the remaining tablespoon of butter, and the uncooked rice. Stir everything well and bring it to a boil. Reduce the heat to a simmer, cover tightly, and let it cook for 10 minutes to allow the rice to start absorbing the liquids.

5-After that, add the sliced mushrooms, replace the cover, and cook for another 5 to 10 minutes without stirring, based on the rice package instructions. Turn off the heat and let the mixture stand covered for 10 minutes; this helps the rice finish cooking perfectly.

6-Gently stir in the cooked ground beef, cream of mushroom soup, milk, sour cream, and half of the cheddar cheese to combine everything. Transfer the mixture to a lightly greased 9×13 inch casserole dish and top with the remaining cheddar cheese. Cover and bake for 20 minutes, resulting in a bubbly, golden dish that’s ready to serve.