Rinse, peel and slice carrots. Peel onions, chop finely and sauté in butter. Add carrot slices to onion, dust with powdered sugar and sauté over medium heat. Stir cream into carrot mixture, cover and simmer until soft, about 8 minutes. Season carrot mixture with salt and pepper. Rinse and trim snow peas and blanch in boiling salted water for about 5 minutes. Rinse snow peas with cold water and drain well.
Fill a large, shallow baking dish with hot water and set on middle rack in oven. Preheat oven to 180°C (approximately 350°F). Puree carrot mixture and gradually stir in eggs and egg yolks. Fold snow peas into carrot mixture and season with salt and pepper. Generously grease a metal bowl with a round bottom with butter. Arrange snow peas in a star shape in bottom of prepared bowl. Spread carrot mixture into bowl and smooth top. Cover bowl with aluminum foil and prick holes in the foil. Place metal bowl on an inverted soup bowl in pan of water in oven and bake for about 1 1/2 hours. Invert bowl to remove souffle. Refrigerate souffle for about 3 hours before serving.