Step 1: Prepare Your Oven and Pasta
Preheat your oven to 375°F (190°C). Grease your 9×13-inch baking dish with butter or cooking spray and set aside. Bring a large pot of water to a rolling boil over high heat. Add 2 tablespoons of salt to the water (it should taste like the ocean). Add pasta and cook according to package directions until al dente, usually 8-10 minutes. You want it slightly firm since it will continue cooking in the oven. Drain pasta in a colander and set aside. Do not rinse—you want the starch to help sauce cling to pasta.

Step 2: Make the Cream Sauce Base
While pasta cooks, start your sauce. In a large saucepan over medium heat, melt the 4 tablespoons of butter. Once melted and foamy, add minced garlic and cook for 1 minute, stirring constantly until fragrant but not browned. Sprinkle the flour over the butter and garlic, stirring continuously with a whisk. Cook this roux for 2-3 minutes, stirring constantly, until it turns a light golden color and smells slightly nutty. This step is crucial for removing the raw flour taste.

Step 3: Add the Liquids
Slowly pour in the heavy cream while whisking constantly to prevent lumps. Then add the milk and broth, continuing to whisk. Bring the mixture to a gentle simmer over medium heat, whisking frequently. The sauce will begin to thicken after about 5-7 minutes. It should coat the back of a spoon nicely. If it seems too thick, add a splash more broth or milk. If too thin, let it simmer a bit longer.

Step 4: Add the Cheese and Seasonings
Reduce heat to low. Add 1½ cups of the mozzarella cheese, ¾ cup of the Parmesan cheese, and all of the cheddar cheese. Stir continuously until all cheese is melted and the sauce is smooth and creamy. Add the Italian seasoning, salt, pepper, nutmeg, and red pepper flakes if using. Taste and adjust seasonings as needed. Remember, the pasta and breadcrumb topping will also add flavor, so don’t over-salt at this stage.

Step 5: Combine Pasta and Sauce
Add the drained pasta to the cheese sauce. Using a wooden spoon or spatula, gently fold everything together until every piece of pasta is coated in that glorious creamy sauce. Be thorough but gentle—you don’t want to break the pasta. The mixture should be very saucy and creamy; it will thicken as it bakes.

Step 6: Transfer to Baking Dish
Pour the pasta mixture into your prepared 9×13-inch baking dish, spreading it into an even layer. Sprinkle the remaining ½ cup mozzarella and ¼ cup Parmesan cheese evenly over the top.

Step 7: Prepare the Breadcrumb Topping
In a small bowl, combine the panko breadcrumbs, 2 tablespoons melted butter, and ¼ cup Parmesan cheese. Mix with a fork until the breadcrumbs are evenly coated with butter. This creates that amazing golden, crispy topping. Sprinkle this mixture evenly over the cheese layer.

Step 8: Bake
Cover the baking dish loosely with aluminum foil (spray the underside with cooking spray to prevent cheese from sticking). Bake for 15 minutes covered. Then remove the foil and bake for an additional 12-15 minutes uncovered, until the top is golden brown and bubbly around the edges. If you want an extra crispy top, turn on the broiler for the last 2-3 minutes, watching carefully to prevent burning.

Step 9: Rest and Serve
Remove from oven and let the baked pasta rest for 5-10 minutes before serving. This allows the sauce to thicken slightly and makes it easier to serve neat portions. Garnish with fresh chopped parsley and serve immediately while hot and bubbly.