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