Preheat the oven to 170 C/338 F Fan forced and line 2 large baking trays with baking paper
Melt the butter and whisk in erythritol and vanilla extract. Allow to cool.
Combine the almond meal, coconut flour, baking powder, xanthan gum and salt in a large bowl. Blend to ensure the baking powder is well dispersed.
Whisk the egg into the butter mixture. Add the butter mixture to the dry ingredients and stir until well combined. Make sure cookie dough is cool enough to gently fold through the white choc chips and the macadamia nuts. Allow the dough to sit for about 5 minutes.
Depending on the size of the cookies you want, use a teaspoon or tablespoon and create balls out of the cookie dough. Roll into firm balls and squash the balls down into a cookie shape onto the baking paper. Use your hands to shape the edges for a smoother shape.
Bake for 10-14 minutes or until cookies have browned slightly and are cooked through. You may need to rotate or turn the tray if the cookies aren't cooking evenly. Bake for less time for a softer cookie and more time for a crisper cookie but watch that the white chocolate doesn't overcook.
Allow cookies to cool completely on the tray before moving to a cooling rack for a couple of hours or until they crisp up. Store in an airtight container.
Note that pure Erythritol will give you a crispy finish. Using alternate sweeteners will vary the results.Xanthan Gum will make these cookies chewy and they will bind more. Feel free to omit but the end result of the texture will vary.I like to use Vitawerx white chocolate blocks and chop the chocolate into small bits about the size of choc chips. Make sure you stay posted for a home made white chocolate that will be brilliant to use in this recipe.