Preheat your oven to 375 degrees Fahrenheit.

The key to making this quick and easily, is to prepare all of the ingredients before starting.

Using awesome knife skills or a mandolin slicer, slice 3 pounds of potatoes.

Grate 1 medium onion.

Cube 2 cups of leftover cooked ham.

In a large saucepan, melt the butter and add the flour. Stir and cook for 2 minutes. Stirring frequently to form a light roux. Mix the parsley, salt an thyme in with the milk. Then slowly add the milk while whisking to form a smooth mixture. Bring to a boil, reduce and cook for 3 minutes or until the mixture thickens.

While he mixture comes to a boil, grease a 2.5 quart oven safe baking dish with vegetable spray. Create a layer of potatoes, top with 1/3 of the onions and 1/2 cup of the shredded cheese.

Once the sauce is thickened, remove from the heat and spoon 1/3 of the sauce over the layered potato mixture.

Repeat the layering process two more times. Cover the dish and bake for 1 hour 30 minutes.

Uncover and top with the remaining 1/2 cup of shredded cheddar cheese. Place back in the oven and bake for another 20 minutes.

Remove from the oven and serve.