Pat the chicken breasts dry with paper towels, then pound them to an even 1/2-inch thickness—this ensures they cook evenly and quickly. Set up three shallow bowls for your breading station: one with flour mixed with seasoned salt and black pepper, one with beaten eggs, and one with Italian breadcrumbs. I like to add a pinch of extra salt to the flour mixture since it's the first coating to touch the chicken and sets the flavor foundation. Arrange all ingredients within arm's reach before you start cooking, as the breading process moves quickly.

Bring a large pot of salted water to a boil and cook the rigatoni for 1 minute less than the package's al dente time—it should still have a slight firmness since it will finish cooking in the oven. While the pasta cooks, heat your oven to 375°F and grease a 9x13-inch baking dish. Drain the pasta and immediately transfer it to a large bowl. Pour in the marinara sauce, 2 tablespoons of Parmesan, and 1 cup of mozzarella, then toss everything together gently. The residual heat from the hot pasta helps meld these flavors together, and setting this aside while you cook the chicken keeps it warm and ready for assembly.

Heat the vegetable oil and butter together in a large skillet over medium-high heat until the butter foams and the oil shimmers—this combination creates the richest, most flavorful crust. Working with one chicken piece at a time, coat it thoroughly in the seasoned flour, shaking off excess, then dip into the egg wash, and finally press into the breadcrumbs, making sure they adhere well. Carefully lay the breaded chicken in the hot oil and cook for 4 minutes per side until deeply golden brown. Work in batches to avoid overcrowding the pan, which would lower the oil temperature and result in greasy coating instead of a crispy crust. Transfer each piece to a paper towel-lined plate to drain excess oil while you finish the remaining chicken.

Once all the chicken has cooled slightly on the paper towels, slice each piece into bite-sized pieces—this makes the casserole easier to eat and helps the chicken distribute evenly throughout the dish. I find that letting the chicken rest for just a minute or two on the paper towels makes slicing cleaner and keeps the coating intact without becoming soggy.

Spread half of the pasta mixture from Step 2 into the prepared 9x13-inch baking dish, then layer half of the sliced chicken on top. Sprinkle 2 tablespoons of Parmesan and 1 cup of mozzarella over this layer. Add the remaining pasta mixture, followed by the rest of the chicken, then top with the final 1 tablespoon of Parmesan and remaining 1 cup of mozzarella. Bake at 375°F for 25 minutes until the cheese is melted and bubbling around the edges. For an extra-browned, crispy top, increase the oven temperature to 425°F and bake for an additional 5 minutes, watching carefully to prevent burning.

Remove the casserole from the oven and let it rest for 2-3 minutes before serving—this allows the layers to set slightly and makes plating cleaner. Garnish with fresh chopped parsley for a bright pop of color and freshness that cuts through the richness of the cheese and sauce.