In a large pot, boil potatoes in salted water until fork tender. Drain well and return the potatoes to the pot. Mash the potatoes with a potato masher.

Preheat oven to 350 degrees F.

Add sour cream, butter, milk, salt, pepper, bouillon, garlic salt and garlic powder to the pot of potatoes. Mix well.

Stir in Parmesan cheese, 1 cup cheddar cheese, and half of the bacon.

Pour potatoes into a 9x13 baking dish.

Place in oven at 350 degrees F for 25 minutes.

Remove from oven and top with the remaining cheddar cheese, and bacon. Bake an additional 5 minutes.

Remove from oven and sprinkle with green onions and serve.