Cook the macaroni according to the package directions.
Meanwhile, heat 1 tablespoon butter in a large saucepan over medium heat. Add the bread crumbs and cook, stirring, until golden, 1 to 2 minutes.
Stir in ¼ teaspoon each salt and pepper and the parsley (if desired). Transfer to a small bowl and set aside.
Wipe out the saucepan and melt the remaining tablespoon of butter over medium heat. Add the flour and cook, stirring, for 2 minutes.
Whisk in the milk and cook, stirring occasionally, until the sauce has slightly thickened, 5 to 7 minutes.
Add the Cheddar and ½ teaspoon salt and whisk until the cheese melts. Stir in the macaroni. Divide among bowls and sprinkle with the bread crumbs.