Peel and slice the potatoes as thinly as possible (a mandarin slicer works well for this)

Slice onions as thinly as possible

In 9 x 13 pan, sprinkle a little salt and pepper

Arrange 1/3 of the potatoes along the bottom of the pan

Sprinkle with 1/3 of the sliced onions

Sprinkle 2 TBSP flour over layer

Sprinkle with 1 TBSP minced garlic

Sprinkle with 1 cup of the sharp cheddar cheese

Repeat steps for two more layers

On last layer, add 1 cup Parmesan cheese along with the last cup of sharp Cheddar

In a 4-cup measuring cup, combine 1 can evaporated milk, 2 cups half and half or light cream, and 1 cup chicken broth. Mix well and pour over ingredients in pan

Because the size of potatoes varies, you may need a little more chicken broth. You want the liquid to come up just under the top of the ingredients

Cover pan with foil and bake at 375 for 2 hours. Remove foil and bake another 15 minutes uncovered. Test to make sure potatoes are tender. If needed, bake another 15-20 minutes