Preparation Preheat oven to 400°F. Butter 9-inch-diameter glass pie dish. Blend creamed spinach, grated Swiss cheese, salt and pepper in medium bowl; whisk in egg yolks. Using electric mixer, beat egg whites in large bowl until stiff but not dry; fold into spinach mixture. Gently transfer to prepared dish. Bake soufflé until beginning to color at edges and center is puffed and softly set, about 18 minutes. Meanwhile, purée half of roasted red peppers, 1 tablespoon reserved red pepper juices and balsamic vinegar in processor until almost smooth. Add remaining roasted red peppers and shallot and chop, using on/off turns, until chunky purée forms. Transfer sauce to small saucepan. Stir over medium heat until warmed through; season to taste with salt and pepper. Spoon soufflé onto plates. Serve, passing sauce separately.
Preparation Preheat oven to 400°F. Butter 9-inch-diameter glass pie dish. Blend creamed spinach, grated Swiss cheese, salt and pepper in medium bowl; whisk in egg yolks. Using electric mixer, beat egg whites in large bowl until stiff but not dry; fold into spinach mixture. Gently transfer to prepared dish. Bake soufflé until beginning to color at edges and center is puffed and softly set, about 18 minutes. Meanwhile, purée half of roasted red peppers, 1 tablespoon reserved red pepper juices and balsamic vinegar in processor until almost smooth. Add remaining roasted red peppers and shallot and chop, using on/off turns, until chunky purée forms. Transfer sauce to small saucepan. Stir over medium heat until warmed through; season to taste with salt and pepper. Spoon soufflé onto plates. Serve, passing sauce separately.