In a large pot, cover the Creamer potatoes with water and bring to a boil over high heat. Once boiling, reduce heat to medium-low for 15 minutes or until potatoes have some give when pierced with a sharp knife. Alternatively, microwave the potatoes for three minutes.
Preheat oven to 425°F and line a baking tray with foil or parchment paper.
Mix together chicken, ranch dressing, hot sauce, half the mozzarella cheese, half the cheddar cheese, and cream cheese. Set aside.
Drain potatoes if cooking on stove, and toss with olive oil, salt and pepper. Place on prepared baking sheet and gently smash potatoes with the back of a fork.
Top each potato with buffalo chicken mixture. Bake for 10 minutes.
Remove and top with remaining mozzarella and cheddar cheese. Bake for another 10 minutes or until cheese is bubbling and has turned golden brown.
Remove from oven, top with green onion if using, and allow to cool for 2 to 5 minutes before serving. Potatoes are best served immediately, but can be reheated in oven for 15 minutes at 425°F within two days.