Preheat the oven to 375° F. Line a 24-cup mini cupcake tray and a 12-cup mini tray with paper cups.

Put the beets on a sheet of aluminum foil and drizzle or spray with a bit of oil. Enclose them in the foil and place in a pie dish or cake pan. Add about 1 cup water to the pan. Bake beets for about 1 hour or until they can be easily pierced with a fork. Remove beets from the foil, slice in half and then let cool in the refrigerator until chilled. Puree beets in a food processor until very finely chopped.

Combine the almond milk and vinegar in an 8-cup measuring cup and set aside.

Sift together the flour, cocoa powder, baking soda, baking powder, salt, cinnamon and pepper. Add the sugar, oil and vanilla to the milk mixture. Add the beet puree and whisk very well until frothy. Add the dry ingredients a bit at a time until combined, then whisk well until the larger lumps are gone.

Pour the batter into the cupcake trays until about 2/3 full. Place the trays in the center of the oven and bake for 15 to 20 minutes, or until the cakes are springy and dry on the top and the sides pull away from the pan. Let cool in the pan for 10 minutes, and then remove to a cooling rack. When the surface is cool to the touch, sift a bit of cocoa powder over the tops. Follow with a dusting of cinnamon and black pepper too, if desired.