
Preheat the smoker. Set your favorite smoker to 275 degrees F with a mild wood, like cherry or apple.
Prepare the onions. Slice the onions into ¼-inch thick rings using a sharp knife, then arrange them evenly in a 9x13 baking dish.
Add the toppings. Place the butter pads on the onions, then sprinkle on the shredded cheeses. Next, sprinkle the Spicy Sweet Rub evenly onto the dish.
Smoke the onions. Place the prepared baking dish or pan on the smoker grates, close the lid, and allow to cook for 2-3 hours. If you prefer softer onions, go closer to 3 hours. Once the cheese is crispy and the onions are slightly translucent, remove them from the smoker.
Serve and enjoy. Serve your Tennessee Onions as a casserole, or as a side or topping for BBQ. Enjoy!