Cook, whisking often, until mixture is thick and bubbly and coats the back of a wooden spoon, 6 to 8 minutes. Stir in cayenne, if using, and 1 cup each yellow and white cheddar cheese. Season with 1 teaspoon salt and 1/4 teaspoon pepper.
Toss pasta with cheese mixture; fold in ham. Transfer to a 9-by-13-inch baking dish or individual dishes (see note). Set aside.
In a food processor, pulse bread until large crumbs form. Toss together with remaining 1/4 cup each white and yellow cheddar, and 1/4 teaspoon salt. Top pasta with breadcrumb mixture. Bake until top is golden, about 30 minutes.
Servings: 8 very generous portions
Time to Prepare: Prep: 30 minutes; Total: 1 hour
Submitted By: Dellaina
Original Source: Everyday Food Magazine
Martha's Note: This recipe makes enough to fill eight 12-to-16-ounce baking dishes. Divide the macaroni and cheese evenly, sprinkle with topping, and bake for 15 to 20 minutes, until golden.
Dellaina's Note: This recipe made tons! We had plenty left over for lunch the next day.