In a saucepan, whisk together sugar and cornstarch until combined. Add milk and whisk until smooth. Whisk in eggs, then egg nog. Heat pan over medium high heat to a full boil. Drop heat to medium and whisk for 1 minute. Turn off heat, whisk until smooth.
Place pudding into medium bowl and cover pudding so plastic wrap touches surface of cream but peel it back 1/4” on one of the sides to allow steam to escape and prevent a ‘skin’ from forming. Place pudding in fridge to cool (about 2 hours).
Spoon cooled pudding into decorative bowls. Garnish with fresh berries.