Combine the eggnog and cornstarch in a medium saucepan. Whip until smooth. Stir in the cinnamon and nutmeg.

Bring to a boil. Let boil for 2 minutes. Remove from the heat and stir in the sour cream.

Beat whipping cream and sugar in a separate bowl until stiff peaks form. Fold into the eggnog mixture.

Serve with your favorite cookies.