Preheat the oven to 400 degrees F (200 degrees C). Lightly coat a 9x13-inch baking dish with cooking spray.

Place 1 layer sliced onions in the prepared baking dish; sprinkle with some soup mix, 1 layer bacon pieces, 1 layer potato slices, 1 layer cheese, and some cream. Continue layering onions, soup mix, bacon pieces, potato slices, cheese, and cream, ending with a cheese layer.

Coat a piece of aluminum foil with cooking spray; cover the baking dish with foil, coated-side down.

Bake in the preheated oven until potatoes and onions are tender, 40 to 50 minutes. Remove foil; continue baking until nicely browned and bubbly, about 10 minutes more.