Preheat oven to 400 degree F. Lightly grease a baking sheet; set aside. To assemble sandwiches, spread 1 side of each of the frozen French toast slices with honey mustard. Layer 3 of the toast slices, mustard sides up, with the turkey, ham, and cheese. Cover with remaining toast slices, mustard sides down.
Place sandwiches on prepared baking sheet. Bake in preheated oven for 15 to 20 minutes or until sandwiches are heated through, turning sandwiches over once. Cut each sandwich in half diagonally. Makes 6 half sandwiches.