Asparagus Au Gratin

4 tablespoons butter
1/4 cup flour
1 3/4 cup chicken stock
1/4 cup half and half
3/4 cup grated Cheddar cheese
1/4 cup grated Parmesan cheese
salt and freshly ground pepper to taste
3 bunches, hot, freshly cooked asparagus spears

Preheat oven to 450 degrees.

Butter a casserole dish. In a saucepan melt the butter, add the flour and stir with a wire whisk until blended.

Meanwhile, bring the chicken stock and half and half to a boil and add all at once to butter flour mixture, stirring vigorously with the whisk until the sauce is thickened and smooth.

Add the cheddar, Parmesan, salt and pepper and stir until the cheeses melt.

Alternate layers of sauce and asparagus in a buttered casserole, ending with a layer of sauce.

Sprinkle with additional Parmesan cheese and brown quickly under a preheated broiler or bake in a preheated 450F oven for 5 minutes.