Prepare the Choux Pastry: Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper.

In a medium saucepan, combine water, butter, and salt. Bring to a boil over medium heat.

Reduce the heat to low and add the almond flour, coconut flour, and xanthan gum. Stir vigorously until the mixture forms a ball and pulls away from the sides of the pan.

Remove from heat and let the mixture cool for a few minutes.

Transfer the dough to a mixing bowl. Add the eggs one at a time, beating well after each addition until the dough is smooth and glossy.

Spoon the dough into a piping bag fitted with a large round tip. Pipe small mounds onto the prepared baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 20-25 minutes, or until the puffs are golden brown and have risen.

Turn off the oven, prop the door open slightly, and let the puffs cool in the oven for 10-15 minutes to prevent them from collapsing.

Transfer to a wire rack to cool completely.

Prepare the Cream Filling: In a large mixing bowl, beat the heavy whipping cream, erythritol, and vanilla extract until stiff peaks form.

Once the puffs are completely cool, use a sharp knife to cut them in half horizontally.

Spoon or pipe the whipped cream filling into the bottom half of each puff, then replace the tops.