Bring a large pot of water to a boil. 

Drop the peeled and cubed potatoes into the water and boil until fork tender. 

Drain the potatoes and return the pot to the stovetop. 

Add the butter to the pot and melt. Add the onion and garlic to the hot butter and cook for about 5 minutes. 

Add the milk, sour cream, salt, pepper, garlic powder, and onion powder. Heat through then set aside.

Push the potatoes through a ricer into the milk/cream mixture, or alternatively, add the potatoes to the cream and cream with a hand mixer. Combine well with the cream and butter mixture. 

Fold the cheese into the mashed potatoes, taste, and season with more salt and pepper to your taste.