Preheat oven to 350 degrees F. Cook macaroni according to package directions, adding broccoli and sweet pepper about the last 1-2 minutes. Combine macaroni mixture and ham in a separate casserole dish and set aside.
In a small saucepan, stir milk and cornstarch, as well as pepper. Cook and stir until thick and bubbly, but DO NOT leave unattended as milk cooks fast! Add cheese until melted. Stir into macaroni mixture in casserole. Combine bread crumbs and butter and sprinkle on top!
Cook in oven 45 minutes. Should be bubbly and bread crumbs will be light brown!