In a large mixing bowl using a hand mixer or in the bowl of a stand mixer, combine the butter and almond butter. Beat until creamy and homogenous.
Add the collagen, psyllium husk and brown sugar substitute. Beat until well combined.
Add in the eggs and vanilla and again beat until well combined and creamy.
Add all of the dry ingredients: salt, baking soda, cream of tartar, cinnamon and almond flour. Combine well.
At this time, the dough should not be too sticky to handle, but if you need or want to refrigerate for a little while, you certainly can.
Line baking sheets with parchment paper and preheat oven to 325 degrees.
Combine the cinnamon and sugar blend on a plate or pie pan. Scoop dough and drop into the cinnamon sugar blend. Then roll dough into balls and place on the prepared baking sheet. Flatten the dough balls with a glass or the palm of your (clean) hand.
Bake for 13-15 minutes. Watch them carefully. The allulose browns easily and will also burn easily. You want the cookies just slightly cracked on the surface and the bottoms very lightly browned.
Remove cookies to a cooling rack to cool completely. These cookies will be soft and chewy and are best kept in the refrigerator.