Peel and cut the potatoes into pieces that are generally the same size. Bring a large pot of water to a simmer and add the potatoes. Bring to a boil and cook until the potatoes are cooked through, 30 to 35 minutes. (When they're cooked through a fork should easily slide into the potatoes with no resistance, and the potatoes should almost, but not totally, fall apart.)
Preheat the oven to 350 degrees F.
Drain the potatoes thoroughly 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 butter, cream cheese and about 1/2 cup of half-and-half. Mash, mash, mash! Next, add about 1/2 teaspoon seasoning salt and 1/2 teaspoon black pepper. Stir well, and then taste and add more half-and-half, seasoning salt and pepper if needed.
Transfer the potatoes to a medium-sized baking dish. Throw a few pats of butter over the top of the potatoes and place in the oven until the butter is melted and the potatoes are warmed through.
This dish can be made 1 to 2 days in advance. Follow the recipe up to putting the mashed potatoes in a baking dish and then refrigerate. Take the potatoes out of the fridge 2 to 3 hours before serving time. Bake in a 350-degree-oven until warmed through, 20 to 30 minutes.