2. Cook the corn in 1 quart boiling water and 1/2 teaspoon salt until tender, about 2 minutes. Drain the corn in a colander and let cool. Puree ½ cup of the corn kernels in a food processor. Add salt to taste, sugar, nutmeg (if using) and egg whites and process until just mixed. Transfer the mixture to a mixing bowl and stir in the flour, then the remaining corn kernels. (Don't mix them in the food processor, because you want to keep the remaining kernels whole.)
3. Spray the hot baking sheets with oil (or drizzle the oil on it and spread with a wooden spoon) Spoon small mounds of corn mixture onto the baking sheets to form 2-1/2 inch pancakes, leaving 1 inch between each latke.
4. Bake-fry the latkes in the oven until golden brown, 6 to 8 minutes per side, turning once with a spatula. (When you turn the latkes, try to flip them onto spots on the baking sheet that still have oil.)
5. Transfer the cooked latkes to a plate lined with a paper towel. Continue cooking the latkes in this fashion, stirring the batter before using and adding fresh oil as needed.
6. Serve the latkes hot with the sour cream and/or the preserves.