Preheat oven to 375 degrees. Cook ziti according to package directions; drain.
In saucepan, melt butter over medium heat. Add the dry mustard, salt and pepper and stir. Add in the flour and continue stirring the mixture until it becomes a "roux". (It should have a thick, paste-like consistency.)
Add the milk to the roux and continue stirring over medium low heat until the the mixture becomes thick and bubbly. (It helps speed the process along if you warm the milk in the microwave first!)
Remove the saucepan from the heat and add the shredded cheese. Stir until the cheese is melted.
Put ziti into baking dish or casserole and top with the cheese mixture. Stir to be sure ziti is coated with the cheese mixture.
Sprinkle bread crumbs over the top and add tomato slices if desired.
Bake in 375 oven until very slighly browned on top, about 30 to 45 minutes.
Try mixing cheeses for variety -- part cheddar part monterey jack maybe?
Submitted by: Lisa M. Rohner
