In the bowl of a stand mixer fitted with the paddle attachment, combine the almond flour, cocoa powder, tapioca starch, sugar, cinnamon, salt, and cayenne. Add the pecans, butter, and vanilla. Mix on low until the butter is incorporated and the dough forms large clumps, 1 to 2 minutes. If you don’t have a stand mixer, use a pastry cutter to blend the butter into the dough. Cover the dough with plastic wrap and refrigerate for 30 minutes.