Cook butter and garlic in a medium skillet over medium-low heat, swirling pan often, until foaming subsides and garlic is fragrant, about 2 minutes. Add panko and stir to coat evenly. Cook, stirring often, until panko is golden brown, about 4 minutes. Discard the garlic. Transfer bread crumbs to a plate to cool while you prepare the rest of the ingredients.
In a large bowl, combine cooked pasta, shredded chicken, marinara sauce, salt, pepper, 1 cup of mozzarella and ½ cup Parmesan.
Transfer mixture to a greased 12-inch cast iron skillet or large baking dish. Cover with foil and bake until heated through and bubbly, about 25 minutes.
Remove the cover and sprinkle with remaining 1 cup of mozzarella, remaining ¼ cup of Parmesan, and toasted bread crumbs. Return to the oven until the cheese melts, about 5 more minutes.
Let stand for about 5-10 minutes. Garnish with chopped fresh basil or parsley just before serving.
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Notes
Use Panko bread crumbs instead of regular bread crumbs. Panko gives the topping a delicious, crispy texture that's similar to the fried coating on traditional Chicken Parmesan!
Bake the casserole just until it's heated through. All of the ingredients are already cooked, so you just want to warm it in the oven until bubbly. Don't bake it for too long or it will dry out and the pasta will get mushy.
For an extra-cheesy casserole, add little balls of fresh mozzarella to the mix, or include a layer of sliced fresh mozzarella in the dish. You can also slice some extra fresh mozzarella on top!
Any short pasta shape will work, so try penne, rotini, macaroni, medium shells or farfalle.
Stir in some veggies!If your kids like peas, spinach, zucchini, or frozen broccoli, stir that into the dish as well! If you’re using a larger vegetable with a longer cooking time (like broccoli), you may want to steam the vegetables first before adding to the dish. For something small like frozen peas, you can just add them (still frozen) straight to the bowl with the rest of the ingredients.
Cooking for a Smaller Family? Cut all of the ingredients in half and bake the casserole in an 8-inch square dish. The baking instructions remain the same. You can even prepare the full recipe, but divide the ingredients between two 8-inch pans and freeze one casserole for later.