Preheat oven to 375℉
Into a large bowl, begin crumbling the thawed tater tots with your hands.
In a small saucepan, melt the butter and then add diced onions. Season with a bit of salt and pepper. Cook, stirring occasionally, until onions are translucent. Then add the garlic powder and let cook for an additional minute before removing from heat to let cool slightly.
Into the bowl with the crumbled tater tots, add cream of mushroom soup, sour cream, shredded cheese, slightly cooled butter/onion mixture, black pepper, salt (if needed) and green chiles and/or bacon crumbles (if using). Stir until everything is well combined.
Transfer to a greased 9x13 baking dish, spreading the mixture out evenly in the dish.
Transfer to oven and bake for 45 minutes-1 hour or until a bit crispy on top.
To thaw the tater tots, I will generally just leave them in the refrigerator overnight. However, in a pinch, you can use the defrost feature of a microwave to thaw.