1. Preheat your oven to 350 degrees. Melt the butter in a small pot. Add the onions, and cook for 5 minutes. Stir in the dijon mustard & dry ranch and cook until the onions are soft.
2. Slice the rolls in half all at once & place the bottom half in a 9×13 casserole dish. Spread on ¾ of the onion mixture; top with the turkey, bacon, cheese, & top half of the buns. Spread the remaining onion mixture on top of the buns. Bake for 15-20 minutes. Remove from the oven, and slice down the seems to make individual sliders.