Preheat oven 350°F. In blender or food processor, combine corn, heavy cream, and buttermilk. Add eggs, sugar, flour, pepper, and one teaspoon salt and blend until well mixed.
Grate two zucchini with a handheld grater. Sprinkle grated zucchini with remaining salt, toss well, and let stand for 10 minutes. Squeeze in kitchen towel to remove excess liquid, then stir into corn mixture along with red bell pepper. Grease timbales (molds) with butter. Using a mandolin, slice remaining zucchini into thin strips and lay in cross pattern to line timbales. Divide corn mixture evenly among molds.
Place timbales in baking pan. Pour hot water into pan to reach halfway up sides of molds. Bake for 45 minutes. Remove molds from baking pan and let stand for several minutes. To remove timbales from molds, run knife around edge of each mold, place plate on top, and turn timbale out on plate.