Add butter and cream to a saucepan over medium heat and stir occasionally until the butter is fully melted. Then add the garlic powder and seasoning, and cook until the mixture is just heated through, but not boiling.
Layer half the potatoes into an 8×8 casserole dish, overlapping them as needed. Pour half the cream mixture over top, then sprinkle on half of each cheese. Repeat the process for a second layer, ending with the cheese.
Bake uncovered for 60-75 minutes, or until a paring knife slices through the potatoes with little pressure.
Let potatoes rest for 10 minutes, then serve as desired.
