Instructions

• Preheat oven to 350°F (175°C). Spray a 9×13-inch (or slightly smaller) baking dish with cooking spray.
• Bring a large pot of salted water to a boil. Add 8 ounces rigatoni and cook according to package directions until al dente. Drain the pasta and set aside.
• While the pasta cooks, melt 2 tablespoons butter in a large skillet over medium heat. Add 1 cup diced onion and cook, stirring occasionally, until the onion is soft and translucent, about 4–6 minutes.
• Reduce heat to medium-low. Add 1 (7.5-ounce) container chive onion cream cheese and 3/4 cup heavy cream to the skillet. Stir until the cream cheese melts and the sauce is smooth.
• Stir in 1/2 teaspoon salt, 1/2 teaspoon pepper, and 1/4 teaspoon crushed red pepper flakes. Add 1 (14.5-ounce) can diced tomatoes (drained), 10 ounces frozen chopped spinach (thawed and squeezed dry), and 3 cups diced cooked chicken. Stir until everything is evenly combined and warmed through. Remove the skillet from the heat.
• Add the cooked rigatoni to the skillet and toss gently to coat the pasta in the sauce. Stir in half of the shredded mozzarella and half of the freshly shredded Parmesan.
• Transfer the pasta mixture to the prepared baking dish and spread it evenly. Sprinkle the remaining mozzarella and remaining Parmesan evenly over the top.
• Bake for 20 minutes, until the casserole is bubbly and the cheese is melted. Let rest a few minutes before serving.