Preheat oven to 375°F (190°C). Butter a non-stick muffin pan (for bigger appetites, butter only 10 muffin cups); divide breadcrumbs between cups. Shake and tilt pan to coat all sides of cups well. Discard any excess.
In a large pot of boiling salted water, cook macaroni for about 8 min or until al dente, or according to package directions.
Meanwhile, in a medium saucepan set over medium-high heat, melt butter. Sprinkle with flour, mustard, salt and pepper; cook, whisking, for 1 min. Gradually whisk in milk. Bring to a boil and reduce heat. Whisk for 3 to 5 min or until smooth and thickened. Remove from heat; stir in 2 cups (500 mL) Cheddar until melted and smooth.
Drain macaroni and return to pot. Pour cheese sauce over pasta; stir until coated.
Divide mixture evenly among muffin cups. Sprinkle with remaining cheese. Bake for 20 min or until hot. Let stand for 10 min. Run a small knife around each muffin, then ease out of cup.
Video
Notes
The dry breadcrumbs help prevent the muffins from sticking to the pan.