01 - Cook elbow macaroni in a large pot of boiling salted water until just al dente, then drain well.
02 - In a saucepan over medium heat, melt butter. Whisk in flour and cook, stirring constantly, until mixture is bubbling but not browned. Gradually whisk in milk; continue cooking and whisking until the sauce thickens. Stir in shredded cheddar until melted and smooth. Season with salt and black pepper.
03 - Add cooked macaroni to the cheese sauce, stirring until well coated.
04 - Transfer macaroni and cheese mixture to a greased baking dish. Evenly sprinkle breadcrumbs over the top. Bake in a preheated oven at 375°F (190°C) for 20 minutes, or until golden brown and bubbling.