In a large microwave safe bowl, mix Velveeta, cream cheese, milk and butter. Cook on high until melted and smooth (approx. 10-15 minutes). When done add salt and pepper to taste. Cook macaroni according to instructions minus 3-5 minutes and strain.
Pour half of the macaroni in a large baking dish, pour half the cheese mixture on top and top with half the cheese crumbles. Repeat with remaining macaroni and cheeses.