Ingredients
Method
Grate ½ cup (1 stick) plus 2 Tbsp. frozen unsalted butter on the large holes of a box grater. Transfer butter to a small bowl, cover, and freeze until ready to use, at least 15 minutes and up to 12 hours.
Meanwhile, whisk 1 large egg and ¾ cup plus 2 Tbsp. chilled heavy cream in another small bowl until very smooth; chill until ready to use.
Rub ½ cup (100 g) granulated sugar and 2 Tbsp. finely grated lemon zest or other citrus zest (such as grapefruit, orange, or lime) together with your fingers in a large bowl until mixture is fragrant and sugar starts to look moist, about 1 minute. Add 3 cups plus 2 Tbsp. (390 g) all-purpose flour, 1 Tbsp. plus 1½ tsp. baking powder, and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt; mix with a fork to combine. Add butter and toss to coat and evenly distribute. Add egg mixture and mix with fork until just combined with a few bits of dry flour remaining. Add 1 cup (140 g) fresh blueberries. Using your hands, knead in bowl just until a shaggy dough comes togethe (don’t worry if some blueberries are crushed).
Turn out dough onto a lightly floured surface, gather together, and knead gently a couple times until a rough but cohesive dough forms (it will still be slightly crumbly in places but should not fall apart). Using a bench scraper or knife, cut dough in half. Stack halves on top of each other, then press down on dough and shape into a 7" disk about 1½" thick. Cut disk in half, then cut each half into 4 equal wedges. Transfer scones to a parchment-lined baking sheet, spacing evenly apart. Freeze until firm, about 30 minutes. (If a baking sheet won’t fit in your freezer, freeze scones on a plate, then transfer to baking sheet to bake.)
Place a rack in middle of oven; preheat to 375°. Brush scones with cream and sprinkle with demerara, raw sugar, or granulated sugar.
Bake scones until puffed and tops are golden brown, 30–35 minutes. Let cool on baking sheet at least 10 minutes before serving. Do ahead: Scones can be baked 2 days ahead. Let cool completely, then store airtight at room temperature. Reheat in a 350° oven until warmed through, about 5 minutes, if desired.