Preheat the oven to 350°F (175°C).
Bring a large pot of salted water to a boil. Add the elbow macaroni and cook until al dente, about 7-8 minutes. Drain and set aside.
In a medium saucepan, melt butter over medium heat. Whisk in the flour and cook for 1-2 minutes, stirring constantly, to form a roux.
Gradually whisk in the milk, continuing to stir until the sauce thickens, about 5 minutes.
Remove from heat and stir in the shredded cheddar cheese until melted and smooth. Season with salt and black pepper.
Combine the cooked macaroni with the cheese sauce and mix well.
Pour the mixture into a shallow round baking dish. Sprinkle the breadcrumbs evenly over the top.
Bake in the preheated oven for 20-25 minutes, or until the topping is golden brown and crispy.
Remove from oven and let cool slightly before serving.