Preheat oven to 400 degrees. Rinse, scrub, and dry potatoes. Slice into coins, about 1/2-inch thick. Don't make them too thin or they will crispy too much while baking. Add coins to a large bowl. Add olive oil, salt, pepper, garlic powder, and cayenne. Toss together until potato coins are coated evenly.
Place potato coins on one or two baking sheets in one even layer. Coins can touch but don't let them overlap one another. Bake in preheated oven for 35 minutes, flipping half way through.
While potatoes bake, let's cook the bacon. Chop the bacon into small bits, about the size of grapes. Add to a large skillet and place over medium heat. Cook until crispy. Remove and drain on paper towels.
Once potatoes are done, remove from oven and top each coin with a sprinkle of cheese, about 1 teaspoon. Then, top each coin with three or four pieces of bacon. Place back into oven to melt the cheese, about 2 minutes.
Remove potatoes from oven and transfer to a servings platter. Top each with ½ teaspoon of sour cream. Sprinkle all of the potatoes with sliced green onions. Serve immediately.