Step 1

Melt the butter in a large skillet over medium-low heat. Add the onions and cook for about 10 minutes until they are soft and translucent.

Step 2

When the onions are done, sprinkle flour over them and whisk to combine. Continue cooking the onion and flour mixture until the flour is golden brown, about two to three minutes.

Step 3

Slowly add the milk and continue whisking to prevent lumps. Cook until the sauce has thickened, which usually only takes a few minutes. Add salt and pepper, mix well and remove from the heat.

Step 4

Spray a medium-size casserole dish with non-stick cooking spray or butter the dish. Add half of the sliced potatoes, then half of the cubed ham, and about half of both kinds of grated cheese.

Step 5

Pour on half of the sauce. Repeat the next layer with the remaining potatoes and ham, pour the remaining sauce over the top and sprinkle with the remaining cheeses.

Step 6

Preheat the oven to 375 degrees.

Step 7

Cover the baking dish tightly with aluminum foil or a cover and bake at 350 degrees F. for 40-60 minutes. How long it takes depends on the thickness of the potato slices.

Step 8

Remove the cover and test to see if your potatoes are done by piercing them with a fork. The fork should slide through easily. If not done, continue cooking for another 10 minutes or so. Once the potatoes are fork-tender, remove the cover and bake for another 20-30 minutes, or until the sauce is bubbling and the cheese is golden brown.

Step 9

Remove from the oven and garnish with chopped parsley before serving.