Scalloped Potatoes & ham

ref: https://www.thepioneerwoman.com/food-cooking/recipes/a10593/scalloped-potatoes-and-ham/

Ingredients

2 Tbsp. butter, plus more for the pan
1 yellow onion, chopped
3 cups diced ham
1 1/2 cups half-and-half
1 1/2 cups heavy cream
1/4 cup flour
Black pepper, to taste
3 lb. russet or Yukon Gold potatoes, washed thoroughly
1 cup grated cheddar cheese
1 cup grated monterey jack cheese
Chopped parsley (optional)

Directions

1. Preheat the oven to 350°F. Butter a large casserole dish.
2. Heat the butter in a large skillet. Add the onion and cook until it starts to turn translucent, 1 to 2 minutes. Add the ham and cook until thoroughly heated, 3 to 4 minutes. Remove from the heat and set aside.
3. In a microwave-safe container, combine the half-and-half and cream, and microwave it for a minute or so, until no longer cold. Whisk in the flour and pepper until totally combined; set aside. (You may add salt, but the cheese and ham are salty, so add sparingly.)
4. Combine the 2 grated cheeses. Set aside.
5. Using a mandoline or slicer, slice the potatoes into 1/8-inch thick (very thin) slices. Layer one-third of the potato slices in the prepared casserole dish. Sprinkle on one-third of the ham/onion mixture, then one-third of the cheese, then pour on one-third of the cream mixture. Repeat this twice more, ending with a sprinkling of cheese and the rest of the cream mixture. Cover the dish with foil and bake for 40 minutes. Remove the foil and bake until bubbly and hot, about 20 minutes more, or longer.
6. 6Cut into squares and serve. Sprinkle on chopped parsley, if you'd like!