Preheat the oven to 350 degrees F. Peel and cut the potatoes into chunks. Bring a large pot of water to a simmer and add the potatoes. Bring to a boil and cook until fork tender, 20 to 25 minutes. Drain the potatoes in a large colander. Place them back into the dry pot and put the pot on the stove. Mash the potatoes over low heat, allowing all the steam to escape before adding in all the other ingredients. Turn off the heat and add the 1 1/2 sticks of butter, the cream cheese, heavy cream, seasoned salt, salt and pepper. Mash to combine. Spread the potatoes in a medium buttered baking dish. Throw a few pats of butter if desired over the top of the potatoes and place in the oven until the butter is melted and the potatoes are warmed through, 20 to 30 minutes.