Grease an 8 quart crock pot and turn to high.
Peel potatoes and slice 1/8" thick. Place in a large bowl and cover with cold water. Set aside.
In a medium mixing bowl, add onions, garlic, heavy cream, sour cream, chicken soup, garlic salt, salt, pepper and seasoning. Stir.
Add grated cheese and stir until combined.
Drain water from potatoes. Add a thin layer of cheese mixture to the bottom of the crock pot.
Add a layer of sliced potatoes then spread a few spoonfuls of cheese mixture over potatoes. Repeat layering process ending with cheese mixture.
Add butter to potatoes.
Cover and cook on high for 6-8 hours or low for 8-10 hours.
Recipe adapted from my Cheesy Garlic Scalloped Potatoes.