Preheat the oven to 375 degrees F. Spray the muffin tin with nonstick baking spray or line with paper liners.
In a large bowl, whisk together the flour, oats, sugar, baking powder, nutmeg, cinnamon, cloves, and salt until well blended.
In another bowl whisk together the eggnog, milk, oil, vanilla, and egg until well blended.
Pour the eggnog mixture into the flour mixture and stir with a spatula until combined.
Using a measuring cup, evenly distribute the muffin batter among the 12 cup muffin tin, filling them ⅔ full.
Sprinkle the batter with additional sugar and cinnamon, optionally.
Bake in the preheated oven until a toothpick inserted in the center comes out clean,14-16 minutes.
Remove from the oven and place the muffin tin on a wire rack to cool for about 5 minutes. Then carefully remove the muffins from the tin.