In a mixing bowl beat 4 eggs, then add the yellow cake mix, 1 cup of eggnog, ½ cup of melted butter, 1 teaspoon of vanilla extract, and ½ teaspoon of nutmeg. Beat the batter for 2-3 minutes.
Pour the batter into a greased 9x13 baking dish and bake at 350 degrees for 25-30 minutes. Remove from the oven and allow the cake to cool for 15 minutes.
Tres Leches Soak: Whisk together ½ cup of eggnog, 1 (14 ounce) can of sweetened condensed milk, and 1 (12 ounce) can of evaporated milk. Use a fork to prick holes into the cake. Pour about half the mixture slowly and evenly over the top. Allow it to soak in and then slowly pour the rest over the top of the cake. Refrigerate at least 1-2 hours, or preferably overnight.
In a mixing bowl, beat together 2 cups of heavy cream, ½ cup of powdered sugar, and 1 teaspoon of vanilla extract until stiff peaks form. Spread over the top of the cake, then sprinkle with cinnamon and nutmeg. Keep refrigerated until ready to serve.