1-Step 1: Prepare Your Oven and Baking Dish Preheat your oven to 400 degrees Fahrenheit and position the rack in the middle of the oven. This temperature ensures the cheese melts and browns without overcooking the pasta. Grease a 9×13 baking dish with cooking spray or a light coating of oil. Proper preparation prevents sticking and makes serving much easier.

2-Step 2: Cook the Pasta Bring a large pot of salted water to a boil. Add the penne pasta and cook for about 10 minutes, but stop slightly before the pasta reaches full tenderness. You want it slightly underdone because it will continue cooking in the oven. This technique prevents the dreaded mushy casserole texture that happens when pasta overcooks. Drain the pasta and set it aside while you prepare the beef mixture.

3-Step 3: Brown the Ground Beef In a large skillet, heat the olive oil over medium-high heat. Add the ground beef and chopped onion, cooking together for about 10 minutes. Use a wooden spoon or spatula to break up the meat into small, even pieces as it cooks. This ensures every bite has tender beef throughout. Add the minced garlic during the last couple of minutes of cooking so it becomes fragrant without burning. Once the beef is fully browned and no pink remains, drain any excess fat from the pan.

4-Step 4: Add the Sauce and Season Pour the marinara sauce into the skillet with the browned beef and onions. Stir everything together and let it warm through for 2-3 minutes. Taste the mixture and add salt and pepper according to your preference. Keep in mind that the cheese will add some saltiness, so do not overseason at this stage. The sauce should coat the back of a spoon and have a rich, hearty consistency.

5-Step 5: Combine Pasta and Beef Mixture Transfer the drained pasta to your prepared 9×13 baking dish. Pour the beef and sauce mixture over the pasta and toss gently to combine. Make sure the sauce reaches all the pasta pieces so nothing dries out during baking. For an extra cheesy version, stir in half a cup of shredded cheddar cheese at this stage before adding the top layer. This creates pockets of melted cheese throughout the casserole.

6-Step 6: Add the Cheese Topping Spread the remaining shredded cheddar cheese in an even layer across the top of the casserole. A thick, even layer ensures every serving gets plenty of melted cheese. If you love a crispy cheese top, you can even add a bit more than the recipe calls for. Some home cooks like to mix in a quarter cup of grated Parmesan with the cheddar for added flavor depth.

7-Step 7: Bake to Perfection Place the baking dish in your preheated oven and bake uncovered for 10 minutes. The cheese should melt completely and begin bubbling around the edges. For a golden brown cheese topping, switch your oven to broil for the last 2-3 minutes. Watch carefully during broiling because cheese can go from golden to burnt very quickly. Remove the casserole from the oven and let it rest for about 5 minutes before serving. This resting period helps the casserole set and makes it easier to serve neat portions.