Preheat oven to 400°F.
Cook and drain macaroni according to package directions; set aside.
In a large saucepan melt butter.
Add flour mixed with salt and pepper, using a whisk to stir until well blended.
Pour milk and cream in gradually; stirring constantly.
Bring to boiling point and boil 2 minutes (stirring constantly).
Reduce heat and cook (stirring constantly) 10 minutes.
Add shredded cheddar little by little and simmer an additional 5 minutes, or until cheese melts.
Turn off flame.
Add macaroni to the saucepan and toss to coat with the cheese sauce.
Transfer macaroni to a buttered baking dish.
Sprinkle with breadcrumbs.