In a large bowl, mix together the protein powder, almond flour, coconut flour, xanthan gum, salt, baking soda, and baking powder. Set aside.

In a separate bowl - the bowl of a stand mixer fixed with a paddle attachment, or a large bowl, if using a hand mixer - cream butter and sugar substitutes until smooth and fluffy.

Be sure to scrape down the sides of the bowl a few times, to make sure everything is incorporated into the mix.

Add the eggs, lemon juice, and zest to the mix, beating well to combine.

With mixer turned down to low speed, slowly add dry ingredients mix to the mixing bowl of wet ingredients, and carefully mix until well incorporated and smooth.

Wrap dough ball in plastic film, chill for 1 hour. This is an important step for any gluten free cookie dough, don’t skip it!

Preheat the oven to 350 F, line 2 baking sheets with parchment paper.

Roll 1" balls out of the cookie dough. Gently dip the top of each ball into the sugar substitute, arrange dough balls on baking sheets. Leave at least 2" between cookies - they flatten out a fair amount.

Gently press the tops of each slightly - flatten JUST enough to prevent the dough from rolling.

Bake for 11-13 minutes. Cookies will look puffy, but flatten out as they cool. Do not over bake!

Allow cookies to cool for 2 minutes before removing from cookie sheets. Cool completely before storing in an airtight container