Preheat oven to 450ºF. Spray muffin pan cups with cooking spray.
For mini-sized muffin pan: Place 2-3 tots in each muffin cup. For regular sized muffin pan: Place 4-5 tots in each muffin cup.
Place muffin pan on bottom rack of the oven and bake for 10 minutes. Remove the pan from the oven.
Spray bottom of shot glass or small juice glass with cooking spray. Use it (in a twisting motion) to press the tots in each muffin cup to make potato cups. Return to oven; bake additional 15 minutes or until deep golden brown.
Add 1 tablespoon of cheese to each potato cup. Bake for 4-5 minutes, or until the cheese has melted. Transfer to platter and let cool for 5 minutes.
Add sour cream, bacon, and green onion to each loaded tater tot appetizer cup, and other garnishes. Serve warm.