Preheat the oven to 375 degrees and lightly grease a medium baking dish.

Cook the elbow macaroni in a large pot of salted water until just tender, then drain and set aside.

In a skillet, cook the chopped bacon over medium heat until crisp, then remove it with a slotted spoon and drain on paper towels.

In a saucepan, melt 3 tablespoons of butter over medium heat, whisk in the flour, and cook for one minute to form a roux.

Slowly whisk in the milk and continue stirring until the sauce thickens, then add the salt, pepper, and cheddar cheese.

Stir the cooked macaroni and most of the bacon into the cheese sauce until evenly coated.

Transfer the mixture to the prepared baking dish and sprinkle the breadcrumbs mixed with the melted butter over the top.

Scatter the remaining bacon over the breadcrumbs and bake for 20 minutes until the topping is golden and the edges are bubbling.