Put lettuce, scallions, and eggs in a salad bowl. Cook bacon in a heavy skillet over moderate heat, turning occasionally, until crisp, about 5 minutes. Transfer to paper towels to drain and pour off all but 2 tablespoons fat from the skillet. Add vinegar and sugar to bacon fat and cook over moderate heat, whisking, until sugar dissolves. Whisk in cream, salt, and pepper, then boil until thickened slightly, about 2 minutes. Pour hot dressing over salad and toss well. Season salad with salt and pepper, if necessary, and crumble bacon over top.