Heat oven to 350. Heat butter in a 6-qt saucepan over medium heat. Add flour & cook, stirring until smooth; about 2 mins. Add milk & heavy cream. Simmer until thickened; about 2 mins. Remove from heat & stir in 3/4 of the cheddar & ham, blue cheese, tomatoes, onions, scallions & bacon. Season with salt & pepper, Tabasco & nutmeg. Stir in pasta. Transfer mixture to 9in x 13in baking dish. Sprinkle with remaining cheddar. Top with bread crumbs. Bake until golden brown; about 25 mins.