I often make this ahead and refrigerate, then bake just before serving. Add 15 to 20 minutes to cooking time. Panko (Japanese style) or seasoned Italian bread crumbs can be substituted for bread crumbs. Leftover ham works well in place of the bacon. This is great comfort food and good enough to share with companySource: Unknown
Chop bacon and cook til crisp; drain, reserving 1 Tbsp. drippings. Cook garlic in drippings about 1 minute; set bacon and garlic aside. Whisk cream, half and half, egg and nutmeg in heavy pan to blend. Add 1 1/2 cups cheddar cheese, 1 1/2 cups Fontina cheese and all of the Parmesan cheese. Stir over medium heat til cheeses are melted.
Pour sauce over cooked pasta, stirring to coat. Stir in bacon and garlic. Season to taste with salt and pepper. Pour into buttered casserole dish or 9 x 13 inch pan. Sprinkle with remaining cheeses. Melt butter and toss with breadcrumbs. Sprinkle crumbs over pasta. Bake in preheated 425 oven til sauce bubbles and crumbs are browned, about 30 minutes.