Bring egg whites to room temperature, about one hour.

Butter a 1 1/2 quart, heat-resistant, non-metallic souffle dish or a 1 1/2 quart, heat-resistant, non-metallic, straight-sided casserole and sprinkle with the Parmesan cheese.

Place the 3 tablespoons butter, flour, mustard, salt, pepper and cayenne in a large, heat-resistant, non-metallic mixing bowl and heat, uncovered, 1 minute on full power , or until butter is melted.

Blend flour and seasonings into melted butter.

Gradually add milk, stirring until smooth.

Heat sauce mixture, uncovered, on roast for 4 minutes or until thickened and smooth.

Stir occasionally.

Add the 1 cup shredded cheddar cheese, stirring to mix.

Heat on roast for 1 additional minute or until cheese is melted.

Stir.

While making the sauce, beat egg whites with cream of tartar until stiff, but not dry.

Set aside.

Beat egg yolks until thick and lemon colored.

Add egg yolks gradually to sauce mixture.

Beat well.

Mix about 1/4 of the beaten egg whites with the sauce mixture.

Work quickly and lightly, taking care not to break down the egg whites.

Fold remaining egg whites into sauce mixture.

Carefully spoon souffle mixture into the prepared souffle dish.

Sprinkle the remaining 2 tablespoons of shredded cheese on top of the souffle mixture.

Place the souffle on the center of the turntable in the microwave oven and heat, uncovered, on DEFROST for 15 minutes or until a knife inserted in the center of the souffle comes out clean.