In a large bowl, add grated butter, flour, baking powder, sugar, poppy seeds, & salt until combined. Skip salt if you are using salted butter.
Next add all the wet ingredients - Buttermilk, vanilla essence, lime juice, lime zest, fresh blueberries.
Gently fold everything just until combined. Clumps are good here.
Turn the dough onto a lightly floured surface, make a round circle of 1-inch height. Cut the circle into eight equal parts. Transfer these triangles to a baking tray lined with parchment paper.
Brush the scones with buttermilk & Put the scones in the freezer for at least 15 minutes, while you pre-heat the oven @ 400F
Sprinkle coarse sugar on top & bake for 20-25 mins or until the top is golden and crisp.
Allow the scones to cool down, while you prepare the lemon glaze (this is optional)
Drizzle the glaze on top of the scones and serve warm.