In a large bowl, whisk flour, granulated sugar, baking powder, and salt. Add butter and cut into flour mixture with your hands or a pastry cutter until crumbles are the size of peas. Add blueberries and lemon zest and toss to coat.
Make a well in center of blueberry mixture. Pour egg, buttermilk, almond extract, and vanilla extract into well. Mix with your hands until just combined.
Turn dough out onto a lightly floured surface and pat to an 8" circle. Cut into 8 triangles and arrange on a large parchment-lined baking sheet. Brush scones with melted butter and sprinkle with coarse sugar. Freeze 10 minutes.
Preheat oven to 400°. Bake scones until lightly golden, about 25 minutes. Let cool 5 minutes, then transfer to a wire rack and let cool completely.
In a small bowl, whisk confectioners' sugar, lemon zest and juice, and cream until smooth, adding more cream if needed until desired consistency is reached.
Drizzle glaze over cooled scones.
