Preheat oven to 350ºF and line a baking sheet with parchment paper; set aside. In a large bowl, combine the flour, 1/2 cup of the oats, the brown sugar, and the baking powder. Grate the butter into the flour mixture using the largest holes of a box grater. Mix all ingredients together.
In a small bowl, whisk together the egg, sour cream, and vanilla until combined. Stir in the blueberries. Pour liquid mixture into the flour mixture and gently stir until just combined. Use your hands to bring dough together. If dough seems sticky, refrigerate dough 15 minutes.
Meanwhile, combine the remaining 2 tablespoons oats with the coarse sugar. Sprinkle 1/2 the mixture over a clean surface or cutting board. Form the dough into 2 4-inch rounds using your hands and set them in the oat-sugar mixture; press lightly. Sprinkle the remaining oats and sugar on top so that there is a thin layer on both sides of the dough.
Cut rounds into 6 wedges each with a large knife. Set wedges on prepared cookie sheet at least 1-inch apart. Sprinkle with any remaining oat-sugar mixture. Bake for 24 to 26 minutes or until golden brown.