Preparation

• Preheat oven to 350°. Grease a large, deep baking dish with butter. In a large pot of boiling salted water, cook macaroni, stirring occasionally, until just al dente according to package instructions. Drain, then rinse with cold water.
• In a large bowl (or same pot you used to cook the pasta), toss pasta and butter; season with salt and pepper. Stir in 2 cups cheddar.
• Add half of macaroni mixture to prepared baking dish. Sprinkle Colby-cheddar over pasta mixture, then top with another layer of macaroni mixture (similar to making a lasagna).
• In a medium bowl, beat eggs and milk until combined. Pour over macaroni mixture.
• Cover baking dish with foil and bake macaroni and cheese until cheese is melted and edges are bubbling, 25 to 35 minutes. Do not overbake! It may be a bit jiggly when you take it out of the oven.
• Turn on broiler. Top with remaining 2 cups cheddar. Broil, watching closely, until cheese is melted and golden, about 3 minutes. Let cool slightly to firm up.