Cook macaroni according to package directions; drain. Stir together hot macaroni, 1/4 cup butter, and next 3 ingredients. Spoon into a lightly greased 13- x 9-inch baking dish.
Whisk together milk and eggs; pour over macaroni mixture.
Stir together breadcrumbs and 1/4 cup melted butter. Sprinkle over macaroni.
Bake, covered, at 350° for 45 to 50 minutes. Uncover and bake 10 more minutes or until macaroni and cheese is set and golden.
Note: For testing purposes, we used Chez Whiz for process cheese spread.