Preheat the oven to 350 degrees. Cut the top off of the bulb of garlic, exposing the garlic cloves. Remove some of the papery outer layers, and place on a square on heavy duty aluminum foil. Drizzle with some olive oil and sprinkle with kosher salt and pepper. Bring the corners of the foil up and twist to seal. (Leave some room, don't wrap too tightly.) Bake in the preheated oven for about 45 minutes until garlic is soft. Remove to cool.
Meanwhile, peel and dice potatoes. Place in a large pot and cover with cold water. Add salt and bring to a boil. Simmer the potatoes until tender, about 20 minutes depending on how big your potatoes are.
Drain and return the cooked potatoes to your pot. Mash and add the butter, cream cheese, sour cream, 2 cups cheese, 1/2 of the bacon and 1/2 of the green onions. Remove the garlic bulb from the foil, and squeeze the garlic pulp out of the skin into the potatoes. Mix well and add seasoned salt and pepper.
Transfer to a 9 x 13 inch casserole dish. Top with the remaining cheese. Bake in a 350 degree oven for about 30 minutes until warm. Remove from the oven and top with the rest of the bacon. Return to oven for 5 minutes. Remove from the oven and garnish with the remaining green onion.