Step 1

Preheat the oven to 400 degrees and mist a 9x13 baking dish with cooking spray.

Step 2

In a small dish, stir together the flour, salt, dry mustard, onion powder, and pepper.

Step 3

Place the butter in a medium saucepan and bring over med-low heat. When the butter is melted, add the flour mixture and stir together until the butter and flour are combined into a paste. Cook that for a minute and then slowly whisk in the milk a little at a time until combined into a smooth liquid. Increase the heat to medium-high and cook, whisking semi-regularly, for a few minutes until it starts to bubble and thicken. Add 6 ounces of the shredded cheese and whisk it into the mixture until fully melted. Remove from heat but cover to keep warm.

Step 4

Spread/layer half of the potato slices across the bottom of the baking dish. Sprinkle a bit of salt and pepper over the potatoes and then spread half of the broccoli florets evenly across and follow with the cubed ham. Pour half of the cheese sauce (about 1 ½ cups) evenly over the top of the layered ingredients. Place the remaining potato slices evenly across the dish on top of the cheese sauce layer and sprinkle with a little more salt and pepper. Add the remaining broccoli and ham across the surface of the potatoes. Pour the remaining cheese sauce over the top of the casserole, covering the ingredients.

Step 5

Cover the baking dish with aluminum foil and transfer to the heated oven. Bake for 60 minutes and then remove the foil and check the potato doneness with a fork (should sink in). Sprinkle the remaining 2 ounces of cheese over the top of the casserole and return to the oven for another 10 minutes until the cheese is golden and the casserole is bubbly. Let the casserole rest for 15 minutes so the sauce will thicken before slicing.