Cook potatoes in a large saucepan of boiling water until tender. Drain well. Return to pan. With the burner still on low, mash potatoes with a potato masher for about 5 minutes. Turn off burner. Add softened butter, cream cheese, half-and-half and seasonings. Stir to combine, and if the mixture needs thinning, add more half-and-half or milk. Pour the mashed potatoes into a large casserole dish. Dot with additional butter, cover with foil and bake at 350 for 15 minutes. Remove tinfoil and continue baking for 10 minutes.