Melt the butter in a skillet on medium heat. Add the onions, and cook for 5 minutes. Add in the minced garlic, & cook for another 2 minutes. Stir in the dijon mustard, Worcestershire sauce, & poppy seeds and cook until the onions are soft (about 10 more minutes). Slice the rolls in half all at once & place the bottom half in a 9×13 casserole dish. Spread on 3/4 of the onion mixture; top with the ham, turkey, 8 slices of bacon, cheese, & top half of the buns. Spread the remaining onion mixture on top of the buns – then the remaining 2 slices of bacon, crumbled. Cover with aluminum foil & bake in the preheated oven for 15 minutes. Uncover; sprinkle on the shredded Cheddar cheese, place back in the oven for 1-2 minutes to melt the cheese. Remove from the oven, and garnish with chopped green onions. Slice down the seams to make individual sliders.