In a medium bowl, whisk together all dry ingredients (except brown sugar substitute) until well combined, 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 brown sugar substitute 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 and vanilla extract to the mix, beating well to combine.
If you want to add a really small amount of brown food colouring, do so now. It’s totally optional, and just makes up for some of the brown you lose, by not using molasses.
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 gingerbread dough ball in plastic film, chill for 1 hour. This is an important step for any gluten free cookie dough, don’t skip it!
Line 2 cookie sheets with pieces of parchment paper.
Lightly dust work surface with a little more protein powder, roll dough out to about ¼ inch thickness (can be slightly thicker).
Use a cookie cutter to cut out whatever shapes you’d like, place cookies 2″ apart on prepared cookie sheets.
Cover each baking sheet and chill for 30 minutes.
Preheat oven to 350 F.
Bake cookies in the preheated oven for 8-10 minutes, or until golden brown on the bottom. Keep an eye on them - smaller cookies will be done faster than larger ones will be.
As they come out of the oven, transfer each cookie sheet to a cooling rack. After 5 minutes, cookies can be removed from the pan and allowed to cool on their own.
Note: The secret to perfectly flat cookies for decorating is to place a clean baking sheet over the pan of freshly baked cookies, as soon as they’re taken from the oven. Gently press down, only enough to level them.