Bring large pot of salted water to boil. Add white potatoes; cover partially and cook until almost tender, about 10 minutes. Using strainer, transfer potatoes to large bowl. Return water in pot to boil. Add sweet potatoes; cover partially and cook until potatoes are almost tender but still retain their shape, about 6 minutes. Drain. Transfer to bowl with white potatoes. (Can be made 1 day ahead. Cool; cover and chill.) Cook bacon in very large skillet over medium heat until almost crisp, about 10 minutes. Using slotted spoon, transfer bacon to paper towels and drain. Pour off all but 1/4 cup drippings from skillet. Add onion and bell pepper; cover and cook until tender, about 15 minutes. Mix in potatoes and bacon. Cover and cook 10 minutes. Add cream and cook uncovered until potatoes are tender and coated with sauce, about 3 minutes. Season with salt and pepper. Transfer potatoes to large bowl. Sprinkle with parsley.