Preheat the oven to 350 degrees F and line a baking sheet with parchment paper or a silicone baking mat.
In a large bowl cream the butter and brown sugar substitute until light and fluffy using an electric mixer. Add the vanilla and eggs and continue mixing until well combined.
Add the almond flour, coconut flour, gelatin powder, baking soda, salt, cinnamon, and allspice. Continue mixing until smooth. Then, stir in the grated carrot.
Scoop by the rounded tablespoon onto the prepared baking sheet leaving about 2 inches between each cookie. Then, gently flatten the tops of the cookies. They won't spread much so the size you make them is very close to the size they will turn out. You should have about 28 cookies.
Bake them for 10-12 minutes or until they are beginning to turn golden brown around the edges and the centers are no longer shiny.
When they are removed from the oven they will be very soft and fragile. Allow them to cool completely before removing them from the baking sheet. When cool they should be firm enough to easily handle, but still soft in the center.
While the cookies are cooling, prepare the frosting. Combine the Cream cheese, butter, vanilla, and the sweetener in a medium bowl using an electric mixer until smooth creamy.
Apply about 2 teaspoons of the icing to the bottom of one completely cool cookie and top with another cookie to form a sandwich. Enjoy now or store in the fridge for later.