Preparation

Make the beet purée

• Position a rack in the center of the oven and preheat to 350˚F.
• Gently scrub the beets under cool running water to remove any dirt. Pat dry. Set each beet in the center of a square of aluminum foil large enough to enclose it and wrap tightly. Arrange the wrapped beets, not touching, on a rimmed baking sheet. Roast the beets until tender, 1 to 1-1/2 hours, depending on their size. The beets are done when a paring knife easily pierces to the center of each beet. (If the beets are not the same size, remove the smaller beets from the oven when tender and continue to roast the larger beets until done.) Remove the pan from the oven and place on a wire rack to cool.
• When the beets are cool enough to handle, unwrap and remove from the foil. Wearing disposable gloves, use a paring knife to trim the stem and root ends. Using paper towels, rub each beet to remove the skin.
• Finely chop the roasted beets and then purée them in a food processor, letting the machine run for a couple of minutes until the purée is completely smooth. You should have 1-1/2 cups beet purée.

Make the cupcakes

• Position a rack in the center of the oven and preheat to 350°F. Line a 12-cup standard muffin pan with paper liners.
• Sift together the flour, baking powder, salt, and cinnamon. Set aside.
• In a large bowl, stir together the beet purée, granulated sugar, eggs, canola oil, and vanilla. Using a rubber spatula, stir in one-third of the flour mixture, continuing to stir just until the flour disappears. Do not beat or overmix. Repeat, adding the remaining flour mixture in two batches.
• Spoon the batter into the prepared muffin cups, dividing the batter evenly and filling each cup almost to the top of the liner. Bake until a toothpick inserted into the center of a cupcake comes out clean, 25 to 30 minutes. Let the cupcakes cool in the pan on a wire rack for 10 minutes. Then carefully release the cupcakes from the pan and let cool completely on the rack, about 1 hour.

Make the buttercream

• In the bowl of a stand mixer fitted with the paddle attachment, or in a medium bowl using a handheld mixer, cream the butter on low speed until creamy and smooth. Add the confectioners’ sugar, cream, orange oil, and vanilla and beat on low speed until incorporated, about 2 minutes. Add the orange juice, a little at a time, until the buttercream is fluffy and smooth.
• Spread a thick layer of buttercream on the top of each cooled cupcake, swirling it to create a decorative finish. Alternatively, transfer the frosting to a pastry bag fitted with a medium star tip and pipe the frosting on the top of each cupcake.

  

Make Ahead Tips

The beets can be roasted up to 5 days ahead. Let them cool in their foil packets and refrigerate.

The cupcakes can be made in advance; cover and store at room temperature for up to 2 days or freeze for up to 1 month.