Preheat the oven to 350˚F. Line 2 large baking sheets with parchment paper.
In a medium bowl, whisk together the almond flour, coconut flour, cacao powder, baking soda, salt and cinnamon. Add the coconut oil, maple syrup and vanilla. Stir well to combine. Fold in the chopped chocolate. Refrigerate the dough for 5 minutes to allow the flour to absorb the liquid.
Using a tablespoon measuring spoon or a small ice cream scoop, scoop heaping tablespoon mounds onto the baking sheets, spacing them 2-3 inches apart.
Bake 5 minutes. Rotate the pans and switch their positions. If the cookies have not flattened (if they still look like little mounds), use the back of a metal spatula and carefully flatten them (wipe the spatula clean as needed to prevent sticking). Bake 6 minutes longer, or until the cookies look dry on top (they will still be very soft). Let the cookies cool on the pans for 5 minutes.
Using a thin spatula, carefully transfer the cookies to a cooling rack. Pop the rack in the freezer for 5 minutes, or until the cookies are completely chilled and firm. Do Ahead: The chilled cookies can be wrapped tightly and frozen for up to 2 months.
Line a work surface with wax or parchment paper (this is just to keep things clean). Place half of the cookies flat side up on the paper. Top each with a scoop of ice cream. Top with the remaining cookies, and press down gently to distribute the ice cream to the edges. You can eat the sandwiches right away, or you can pop them onto a sheet tray and freeze them for 5-10 minutes, until firm. Once frozen, the sandwiches can be individually wrapped in wax paper and stored in an airtight container or a ziptop freezer bag.