Preheat oven to 350 degrees.

Separate bagels halves and arrange bottom slices in a 9x13 baking dish.

Layer each sandwich with swiss cheese slice, ham, turkey and another slice of swiss cheese.

Finish with top of bagel.

Whisk together melted butter and dijon mustard.

Drizzle mustard mixture over sandwiches.

Cover tightly with foil and bake for 20-30 minutes until sandwiches are heated through and cheese is melty.

Can be made up to 24 hours ahead and refrigerated prior to baking.