6 tablespoons (3/4 stick) butter or margarine
3/4 cup flour
3/4 teaspoon salt
3-1/2 cups milk
1-1/2 cups shredded Swiss cheese (6 ounces.)
6 eggs, separated
1 pound fresh broccoli
1/4 teaspoon dry mustard
Grease a 15 x 10 x 1-inch jelly roll pan; line with foil; grease foil.
Melt margarine in medium-sized saucepan; blend in flour and salt. Slowly add 3 cups milk, stirring constantly until sauce thickens and bubbles. Remove sauce from heat; pour 1 cup into a small saucepan and reserve.
Add 1/2 cup of the cheese to the larger amount of sauce, stirring until cheese melts.
Beat egg whites in a small bowl with electric mixer until soft peaks form. Beat egg yolks in a large bowl with the same beaters until light and thick, about 3 minutes.
Beat a small amount of the hot sauce into the yolks, then slowly stir in the remainder until the mixture is well blended.
Stir a spoonful of the egg whites into the sauce, then fold in remaining egg whites until no streaks of white remain. Spread souffl? mixture evenly in prepared pan.
Bake in moderate over (325) for 45 minutes or until top is golden and springs back when lightly touched.
Cut broccoli flowerets into 3-inch lengths, then cut into 1/2 inch pieces, reserving a few for garnish. Save remainder of stems for another meal. Cook broccoli in boiling salted water until tender; drain.
Stir dry mustard, 1/2 cup of the cheese and the remaining 1/2 cup milk into reserved sauce in the small saucepan. Stir over low heat until cheese melts.
Remove souffl? from oven; loosen around edges with spatula. Cover a cookie sheet with foil; invert over souffl?. Invert souffl?; remove jelly roll pan and layer of foil carefully.
Spread broccoli evenly over souffl?; sprinkle broccoli with the remaining 1/2 cup cheese. Drizzle with 1/2 cup of the sauce. Starting at the 10-inch side, roll souffl? jelly-roll style, lifting foil to guide it. Lift roll onto heated platter with two wide spatulas. Spoon some sauce over top. Garnish with reserved broccoli and cherry tomatoes, if desired. Cut into thick slices and serve with remaining sauce. This is a lot of trouble, but it's delicious!