Place the flour, baking powder, salt, and sugar in the bowl of food processer. Pulse to combine. Add butter and pulse until the texture of coarse sand with scattered peasized lumps. Transfer to a large bowl and toss in the frozen haskaps.

In a separate bowl, whisk 2 eggs and buttermilk together. Stir the egg mixture into the butter and flour. Stir with a wooden spoon and then gently knead, lifting up from the bottom to incorporate all the flour, until dough holds together.

Transfer dough to a parchment-lined, large baking sheet, dusted with flour. Pat or roll dough out into an even circle about 1-inch thick. Chill in the refrigerator for 30 minutes. Line a large baking sheet with parchment paper. Cut chilled dough into circles using a 2- or 2¼-inch round cutter and place upside down on the baking sheet, leaving about 1½ inches of space between. Gather scraps together, press into a circle again and continue cutting until all the dough is used up. (The first cut scones will be the flakiest, highest-rising ones.)

Brush scones with egg wash and chill for 30 minutes.

Preheat oven to 400° F. Bake scones for 12–15 minutes, until golden brown. Cool briefly before serving with butter, soft whipped cream, and jam.