Preheat oven to 375℉
Grease the bottom of a 9 by 13 baking dish with olive oil
Wash the potatoes under cold water and towel dry.
Slice the potatoes into ⅛-inch slices. (you can use a knife or mandolin)
Place the potato slices in a large pot filled with cold water and soak for 5 minutes.
Drain and pat dry the potatoes so there's no excess water.
Line the bottom of the greased baking dish with a layer of ⅓ of the potatoes.
Pour ¾ cups cream over the top and sprinkle ⅓ swiss cheese and a pinch of garlic powder on top.
Repeat by adding a second layer using ⅓ of the potatoes on top with adding ¾cup of cream and top with the ⅓ gruyere and a pinch of garlic powder.
Repeat for the third and final layer using the remaining sliced potatoes on top and pouring the remaining milk and sprinkling the ⅓ cheddar cheese and remaining garlic powder on top.
You can add salt and pepper to taste.
Cover with foil and bake in the oven for 1 hour or until the potatoes are fork-tender.
At this point remove the foil and continue to bake for 20 minutes or until the cheese and edges are golden brown.
Sprinkle the chives on top.
Serve warm and enjoy!
