Preheat oven to 350 degrees. Scrub potatoes under cool water and set aside to dry. Cook bacon strips over medium heat in a large pan until crisp. Set on paper towels to cool. When cool, crumble bacon into small pieces.
Bring a large pot of water to a boil. Add potatoes and cook until just tender, about 12-15 minutes, depending on size. (Alternatively, pierce potatoes with a fork and microwave on high for about 8 minutes.)
Spread 1 Tbsp. butter on the bottom of a small baking dish that will hold all of the potatoes while allowing space between them (for me, this was a 9x13 inch baking dish). While the potatoes are still warm, place them in the baking dish and gently smash them into the bottom of the dish with the palm of your hand. If the potatoes are too hot to handle, place paper towels or a dish towel between your palm and the potatoes. Dot the top of the potatoes with the remaining butter and sprinkle with salt and pepper. Bake at 350 degrees until the tops of the potatoes become crisp and deep golden brown, about 45 minutes.
Sprinkle the top of the potatoes with the crumbled bacon, cheese and green onion. Return to the oven and bake until the cheese is completely melted, about 5 minutes more. Serve immediately, with sour cream on the side.