Begin by washing, and/or peeling your potatoes.  Then, using a mandolin slicer, thinly slice the potatoes into discs.

Meanwhile, slice up the mushrooms, and place them in a large skillet.  Saute with 1/2 C diced onion, until much of the liquids evaporate.

Combine 1 T corn starch with 1/2 C chicken broth and stir until well combined.  Add to the mushrooms and stir constantly as the mixture thickens.  Then, add in the milk and continue stirring.  Remove from the heat and set aside.

Lightly spray the inside of the crockpot with olive oil.  Then, arrange 1/3 of the potatoes on the bottom of the crockpot.

Lightly spray the inside of the crockpot with olive oil.  Then, arrange 1/3 of the potatoes on the bottom of the crockpot.

Then, sprinkle over 1/6 of each of the cheeses.

Repeat the layers until ingredients run out; reserving the last layers of cheese.

Pour the mushroom soup goodness over the top of the layers in the crockpot.

Then, sprinkle on the cheese

Cover and cook on low for 6-8 hours, or until potatoes are tender.