Cook onions in large saucepan of boiling water 1 minute. Drain and cool. Cut off root ends, then peel. (Can be prepared 1 day ahead. Cover and refrigerate.)
Combine onions and cream in heavy large skillet. Bring to boil over medium-high heat. Cover; boil until onions are almost tender, about 8 minutes. Uncover; boil until liquid is slightly reduced, about 4 minutes. Add bell pepper and zucchini. Cover; cook until almost tender, about 5 minutes. Add corn; reduce heat and simmer uncovered until vegetables are tender and sauce thickens, stirring occasionally, 6 minutes. Season with salt and pepper.
Per serving: 1734 Calories (kcal); 177g Total Fat; (88% calories from fat); 16g Protein; 33g Carbohydrate; 653mg Cholesterol; 194mg Sodium Food Exchanges: 0 Grain(Starch); 0 Lean Meat; 3 1/2 Vegetable; 0 Fruit; 35 Fat; 0 Other Carbohydrates