• Preheat oven to 325° Fahrenheit.
• Lightly grease casserole dish with cooking spray or butter, making sure to cover entire bottom of dish and inner sides of dish. Set aside.

For the Chicken

• Add 1 ½ cups shredded rotisserie chicken, ¼ cup buffalo sauce, and 2 tablespoons ranch dressing to small mixing bowl. Mix ingredients together until well incorporated and chicken is coated in buffalo sauce and dressing. Set bowl aside.

For the Pasta

• Add 16 cups water to large pot. Place pot on stovetop over medium-high heat and bring water to boil.
• Once water begins to boil, add 1 tablespoon salt and stir to incorporate. Continue heating pot until water resumes boiling.
• Add 1 pound uncooked cavatappi to boiling salted water and stir to incorporate. Boil pasta according to package instructions, reducing cook time by 1 minute.
• When pasta is al dente, pour pasta and water into colander and drain well. Transfer drained pasta to large mixing bowl and set aside.

For the Cheese Sauce

• Place large saucepan on stovetop over medium heat. Add ½ cup unsalted butter and heat butter until melted.
• Once butter has melted, add ½ cup all-purpose flour and whisk vigorously to incorporate butter and flour into mixture resembling wet sand. Simmer mixture over medium heat approximately 1 minute, whisking often, until mixture has thickened and become lightly golden.
• Remove saucepan from heat and let mixture cool slightly, then slowly add 2 ½ cups half and half in small increments. Whisk well after each addition, until ingredients are fully combined and mixture is smooth, before adding more half and half.
• Once all half and half is incorporated, repeat process with 1 ½ cups whole milk. Whisk constantly until ingredients are combined into smooth mixture.
• Return saucepan to stovetop over medium heat. Simmer mixture, whisking frequently, until very thick. Consistency should resemble slightly thinned condensed soup.
• Remove saucepan from heat. Add ½ tablespoon salt, ½ teaspoon freshly cracked black pepper, 1 cup shredded fresh cheddar cheese, and 1 cup shredded fresh mozzarella. Whisk until cheeses are completely melted and mixture is smooth.
• Pour smooth cheese mixture into bowl with prepared pasta and stir to fully incorporate pasta and sauce. Add buffalo chicken mixture to bowl and gently fold chicken into pasta.

For the Buffalo Chicken Mac and Cheese

• Transfer half of pasta mixture to prepared casserole dish. Spread pasta mixture out evenly to cover bottom of dish.
• Top pasta layer with 1 cup shredded fresh cheddar and 1 cup shredded fresh mozzarella, sprinkling cheeses evenly across dish.
• Transfer remaining half of pasta mixture to casserole dish, covering layer of shredded cheeses completely.
• Top second pasta layer with 1 cup shredded fresh cheddar and 1 cup shredded fresh mozzarella, sprinkling cheeses evenly across dish.
• Place casserole dish in preheated oven. Bake dish 15 minutes, or until shredded cheeses are melted and bubbly, and top of mac and cheese is lightly golden brown.
• When mac and cheese is baked as desired, carefully remove casserole dish from oven. Set aside and let rest 3 to 5 minutes.
• If desired, top mac and cheese with drizzle of ranch dressing and/or buffalo sauce, blue cheese crumbles, and/or chopped fresh parsley. Serve dish warm.