In a large bowl, whisk together the flour, sugar, baking powder and salt.
Work the butter into the flour with your fingertips or with a pastry blender, until pea size pieces form.
In a small bowl whisk together the heavy cream, sour cream and vanilla.
Stir the cream mixture into flour mixture until a shaggy dough is formed.
Turn the dough out onto a lightly floured surface. Pat the dough into an oval. Spoon dollops of blueberry compote onto the dough. Fold the dough over onto itself 3 times.
Form the dough into a 1-inch thick round, about 6 1/2-inches in diameter. Cut the dough into 8 wedges.
Place the scones 2 inches apart on the prepared baking sheet. Chill the scones in refrigerator for 20 minutes.
Heat your oven to 375ºF. Brush the tops of scones with heavy cream. Sprinkle with coarse sugar.
Bake until the edges look golden brown, about 18-22 minutes.
Blueberry Compote
In a small saucepan over medium heat, cook the blueberries, sugar, cornstarch and lemon juice, stirring until the sugar is dissolved and the blueberries start to release their juices.
Turn the heat down to low and simmer, stirring occasionally, until thick and jammy, about 3-4 minutes. Remove from heat and let cool completely. Cover and store in refrigerator until ready to use.