Preheat oven to 350F. Lightly grease cookie sheet. In a large mixing bowl stir together coconut, flour, cornstarch and salt. Slowly add Eggnog. Fold mixture a few times and add in vanilla extract. Keep folding mix or use hands to blend ingredients together. Add egg whites one at a time. Keeping folding mix until completely blended. Using a large spoon scoop mix into 1-inch diameter drops onto cookie sheet. Bake 15 to 20 minutes or until edges start to brown and crisp.