In a large bowl mix the hamburger, onion soup mix, and milk.
Thinly spread the meat mixture in an even flat layer in a 13in x 9in oven safe baking dish. (Use a rolling pin to smooth out layer if need)
Top with finely chopped onions lightly pressing them down into the meat.
Bake uncovered for 10-15 minutes or until juices in meat run clear.
Once meat is fully cooked, remove from oven and spoon out any remaining liquid in the dish.
Top the meat and onions with a layer of cheese, covering the entire surface. Bake for another 5-7 minutes or until cheese is melted.
While cheese is melting, slice each roll in half, giving each set a top and a bottom. Lightly sprinkle rolls with water and place on microwave safe baking dish. Warm in the microwave for 20 seconds. Set aside
Once cheese is melted take meat out of the oven and slice with a pizza cutter into 12 even small squares. Scoop each square out with a spatula and place between a warmed top and bottom bun.
*What’s really great about this recipe is that the sliders keep well the next day. Just pop them in the microwave whole for about 30-40 seconds and they taste just as good as the night before!