Make the Choux Pastry: In a medium saucepan, combine water and butter. Bring to a boil over medium heat, stirring until the butter is fully melted.
Add the flour and salt to the saucepan all at once. Stir vigorously with a wooden spoon until the mixture forms a ball and pulls away from the sides of the pan. Remove from heat.
Incorporate Eggs: Let the dough cool for a few minutes. Add the eggs one at a time, mixing well after each addition until the dough is smooth and glossy. Stir in the vanilla extract.
Pipe the Puffs: Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper. Using a pastry bag fitted with a large round tip, pipe 1-inch mounds of dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake: Bake in the preheated oven for 20-25 minutes or until the puffs are golden brown and puffed up. Avoid opening the oven during baking. Remove and let them cool completely on a wire rack.
Prepare the Eggnog Cream Filling: In a mixing bowl, combine the heavy cream, powdered sugar, nutmeg, cinnamon, and vanilla extract. Beat with an electric mixer until soft peaks form.
Fill the Puffs: Once the cream puffs are cool, use a small knife to make a slit in the side of each puff. Using a piping bag, carefully fill each cream puff with the eggnog cream until they feel full but not overly so.
Serve: Place filled cream puffs on a serving platter and dust lightly with additional powdered sugar, if desired.
Notes
Arrange the cream puffs on a festive platter and garnish with a sprinkle of nutmeg or cinnamon on top for an extra holiday touch!