Preheat the oven to 350 degrees. Bring a large pot of salted water to a boil and cook the macaroni until just tender. Drain and set aside.
Cook the bacon in a skillet over medium heat until crispy. Remove the bacon, drain on paper towels, and crumble into pieces.
In a saucepan, melt the butter over medium heat. Whisk in the flour and cook for one minute. Slowly pour in the milk while whisking to avoid lumps.
Stir in the salt, pepper, and 1 1/2 cups of the cheddar cheese until the sauce is smooth. Remove from heat.
Combine the cooked macaroni, cheese sauce, and crumbled bacon in the pot. Stir until evenly coated.
Transfer the mixture to a baking dish and sprinkle the remaining 1/2 cup of cheddar cheese over the top. Bake for 20 minutes until the cheese is melted and the edges are bubbly.