Stir the espresso powder into the hot water and set aside.In a glass measuring cup combine milk, eggnog, vanilla, brown sugar, cinnamon and nutmeg; whisk/stir until thoroughly combined.Place in Microwave and cook for 1 minute and 30 seconds, or until the milk starts to froth up.Remove from Microwave and stir/whisk again.Place in Microwave for an additional 30 seconds, or until the milk begins to froth up again.Remove and, while stirring the eggnog-mixture, slowly pour the coffee into the eggnog-.mixture.Top with whipped cream and dust with nutmeg.Serve.