Step 1

Scrub and clean potatoes, then thinly slice potatoes into 1/8 inch thin slices. No need to peel potatoes. Set aside.

Step 2

Pre-heat oven to 350 degrees F.

Step 3

In a medium pot, turn heat to medium and add butter. Once butter is melted, add diced onions and minced garlic. Sauté for 1-2 minute or until they are soft. Avoid over-browning them.

Step 4

Add flour and stir to combine. Once combined, add milk, chicken broth, thyme and salt. Stir and bring to a boil. Continue stirring and cook for a few minutes, or until sauce thickens slightly.

Step 5

Turn off heat and add shredded cheddar, shredded mozzarella and parmesan. Stir to combine. It's okay if cheese does not melt completely.

Step 6

Grease a 9" x 13" casserole. Add 1/3 of the potatoes to casserole, then spread 1/3 of the cheese sauce onto potatoes, then add the next 1/3 of potatoes and cheese sauce, until all the potatoes and cheese are layered. There should be three alternate layers of potatoes and cheese sauce.

Step 7

Cover casserole with aluminum foil, bake for 30 minutes. Uncover casserole and bake for another 35-45 minutes.

Step 8

Cool for 10 minutes. Serve and enjoy!