Preheat oven to 350 degrees.

Split bagels in half and place all of the bottoms in a 9 x 13 pan.

On each bottom layer a slice of cheese, slices of ham, slices of turkey, another slice of Swiss cheese, followed by the bagel top.

Whisk the butter and mustard together and then brush over the sandwiches.

Cover and bake at 350 degrees for 30 minutes. Makes 6 sandwiches.