Step 1: Preheat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish with nonstick spray or a thin coating of butter.
Step 2: In a large skillet over medium heat, add 1 pound of ground beef and 1 diced small onion. Break up the meat with a wooden spoon and cook, stirring occasionally, until the beef is no longer pink and the onion is soft—about 6 to 8 minutes. Transfer the mixture to a bowl and drain off any excess fat.
Step 3: Wipe out excess oil if necessary, then return the skillet to medium heat. Add 2 cloves of minced garlic, ½ teaspoon salt, ½ teaspoon black pepper, and 1 teaspoon paprika. Cook, stirring constantly, for 1 to 2 minutes until the garlic is fragrant and the spices bloom in the fat.
Step 4: In a large mixing bowl, combine the sautéed beef-onion-garlic mixture with 2 cups of cooked white or brown rice, 1 can (10.5 ounces) of cream of mushroom or cream of cheddar soup, ½ cup sour cream, ½ cup milk, 1 cup of shredded cheddar cheese (reserving ½ cup for topping), and ½ teaspoon dried parsley or thyme. If desired, stir in ½ cup of frozen peas or corn for extra color and nutrients. Mix gently until all ingredients are thoroughly coated in a creamy sauce.
Step 5: Spoon the beef-rice mixture evenly into the greased 9×13-inch baking dish. Use the back of your spatula to level the top so that every portion bakes uniformly.
Step 6: Scatter the remaining ½ cup of shredded cheddar cheese over the surface.
Step 7: Place the casserole on the middle rack of your preheated 375°F (190°C) oven. Bake uncovered for 25–30 minutes. It’s ready when the sauce bubbles around the perimeter and the cheese turns a light golden brown.
Step 8: Remove the dish from the oven and let it sit on the counter for 5–10 minutes. This brief resting period allows the sauce to thicken slightly, making it easier to cut neat squares.
Step 9: Cut the casserole into servings and transfer to plates. For a pop of color and freshness, sprinkle chopped parsley, chives, or a few extra frozen peas on top. Pair with a crisp green salad, steamed broccoli, or warm dinner rolls.