Roast the beets: Preheat the oven to 400 degrees. Place beets on a large piece of aluminum foil. Wrap foil around beets. Place foil packet on a baking sheet pan. Roast beets until a paring knife easily goes through them, approximately 45 minutes to 1 hour depending on size of beets. Remove from oven and let cool. Place beets under cool running water and slip skin off. You may want to wear disposable gloves so your fingers to not turn red. Roughly chop the beets. If possible, use a kitchen scale to weigh out 10 ounces of beets.

Reduce oven temperature to 350 degrees. Line two 12-well muffin tins with paper liners. Set aside.

Prepare the batter: In the bowl of a food processor, place the coarsely chopped beets and lemon juice. Pulse until finely chopped, stopping now and then to push the beets back to the bottom of the bowl. Add the oil and buttermilk and process until smooth. Add the eggs, one at a time, and process until combined.

In a separate bowl, combine the flour, sugar, cocoa powder, baking powder, baking soda and salt. Whisk to combine. Add the dry ingredients to the food processor and pulse until combined.

Fill the prepared cupcake liners two-thirds full of batter. Bake for 15 to 18 minutes or until a toothpick inserted in the center of a muffin comes out clean. Allow cupcakes to cool in the pans on a wire rack for 10 minutes. Remove cupcakes and let cool completely.

Prepare the frosting: In a stand mixer, beat the softened butter on medium for 2 minutes. Reduce speed to medium low. Add the vanilla extract, 3 cups of confectioners’ sugar and 2 tablespoons milk. Beat to combine. Add the additional 1 cup confectioners’ sugar and beat for several minutes until light and fl uffy. If frosting is too stiff, add the additional milk.

Place the frosting in a pastry bag fitted with a large star tip. Pipe frosting on the cooled cupcakes. If desired, garnish with sanding sugar.