Preheat oven to 350 degrees F. Spray an 8x8 baking dish with nonstick cooking spray.
Peel the potatoes and cut into 1-inch pieces. Add them to a pot of water and bring to a boil. Cook until the potatoes are tender, then drain. (I like to add 2 teaspoons of Better Than Bouillon to the water, or garlic powder and onion powder.)
While the potatoes are boiling, cook the bacon in a frying pan. Place the cooked bacon on a paper towel and remove any extra grease. Cut the bacon into small pieces.
Add the potatoes to a mixing bowl and pour in half of the half and half. Use a handheld mixer to mash the potatoes. If the potatoes are dry add the rest of the half and half and mix together.
Spread the potatoes evenly in the baking dish. Top with the cheddar cheese and bake 20 minutes, or until the cheese is melted.
Top the cheese with the bacon and green onions.