Advance preparation: (can be done hours before)
Cheese–Swiss and cheddar– grate 1 1/2 cup. Toss with 1/2 tsp cornstarch and 1/2 tsp flour.
Cream sauce–Melt 3 T butter, stir in 3 T flour. Slowly stir in 1 cup milk. Season to taste with pinch salt, 1/4 tsp basil or garlic or both. Stir in grated cheeses, then let sauce cool.
One hour before serving, preheat oven to 425.
Then, butter 2-quart soufflé dish or straight-sided casserole.
Separate 4 eggs. Beat whites until stiff. Beat yolks until thick. Stir yolks into cream sauce first.* Then, gently fold in whites. Pour mixture into buttered casserole.
Bake at 425 for 15 minutes. Reduce heat to 325 until done, about 20 more minutes. Serve immediately.
* The fluffy, stiff egg whites are the last thing you add to your soufflé. So why do you beat the whites first, just to set them aside while you mix and add the yolks? Because, after you use your mixer on the yolks, youd have to wash the beaters with care before trying to whip up egg whites. But, you can take your beaters right out of the whites and use them to froth up the yolks without any problem.