1/2cuprhubarbdiced (or the fruits, nuts, and/or chips of your choice)
1/2cupcold buttermilkplus 2 tablespoons (plus 1 additional tablespoon as needed)
3tablespoonsboiled cider(see notes)
1largeeggseparated
Sparkling sugaroptional
Instructions
Place rack in the center of the oven and preheat oven to 375 degrees F. Line a large baking sheeting with parchment paper and set aside.
Dice butter into small pieces and place in the freezer while you prepare the other ingredients.
In a large bowl or the bowl of a standing mixer fitted with the paddle attachment, stir together the flour, sugar, baking powder, cinnamon, baking soda, and salt.
Cut the butter in with a fork or a pastry blender or place the mixer on low speed. Continue working in the butter until some pieces are the size of oat flakes and some are the size of your thumbnail. The butter pieces may look large, but this is OK. By hand with a spatula, gently fold in the rhubarb.
Whisk together 1/2 cup plus 2 tablespoons buttermilk, the boiled cider, and egg yolk.
Stir into the dry mixture until a soft, moist dough forms. The dough should be somewhat sticky and not at all dry. If it seems too dry, sprinkle in 1 additional tablespoon of buttermilk.
Transfer the dough to a lightly floured work surface, then pat it into a 7-inch disk. Cut dough into 8 wedges. Place the wedges on the prepared baking sheet. For crispier scones, gently separate the wedges. For softer, higher-rising scones, leave the wedges in a circle (I placed mine in a slightly spaced circle for the best of both worlds).
Beat the egg white in a small bowl, then brush over the tops of the scones. Sprinkle generously with sparkling sugar, then bake for 18 to 25 minutes, rotating the pan 180 degrees halfway through. Begin checking at the 18-minute mark (the farther the scones are apart, the more quickly they will bake.) Remove the scones from the oven when they are light golden brown. Cool on a wire rack and enjoy warm or at room temperature.
Notes
ABOUT BOILED CIDER: Boiled cider is a highly concentrated and intensely flavored apple cider. If you do not have it handy, you can substitute additional buttermilk. Or, to make your own boiled cider: Add 1/2 gallon of apple cider to a large (non-reactive) Dutch oven or pot. Over medium-high heat, bring the cider to a boil. Reduce heat to medium-low and let cook, stirring occasionally, for 4-5 hours, or until the cider has reduced to about 1 cup and has a thick, syrupy consistency. Transfer to a small jar and store in the refrigerator.
TOMAKE-AHEAD: Mix and shape the dough into wedges as directed. Then wrap each unbaked scone individually in plastic and freeze until ready to bake. To bake, unwrap the scones and bake, as directed, from frozen. You will just need to add a few minutes to the original bake time.
TO STORE: Scones are best enjoyed the day they are made but can be individually wrapped and stored at room temperature for 2 days.
TO FREEZE: Scones may also be individually wrapped in plastic and frozen for up to 1 month. Defrost in the fridge overnight or at room temperature before serving.