Preheat oven to 350 degrees.

Cut the cauliflower into large bite-size pieces.

Cook the cauliflower in a large pot of salted water. The cauliflower should be tender, but firm. The cooking time is approximately 5 to 6 minutes.

While the cauliflower is cooking, start the cheese sauce.

Melt two tablespoons of butter in a small saucepan.

When the butter has melted completely, add the flour and stir to combine.

Cook the flour for 1 to 2 minutes, stirring occasionally.

Slowly begin to add milk, whisking constantly. With each addition of milk the sauce should thicken.

Add the dry yellow mustard and stir to combine.

Add 4 ounces of cheese. Stir until the cheese is completely melted and the sauce is smooth.

Place the cooked cauliflower into a large casserole dish.

Pour the cheese sauce over the cauliflower.

Sprinkle the remaining 4 ounces of cheese over the cauliflower.

Bake at 350 degrees for 15 minutes or until the cheese is slightly browned.