Heat the oven to 200C/fan 180C/gas 6 and line a large baking tray with baking paper. For the scones, put the flour, baking powder, sugar and ¼ tsp of salt in a large bowl and whisk to combine. Add the butter and rub into the mixture using your fingertips until the butter is in pea-sized pieces. In a jug, whisk together the crème fraîche, vanilla and two of the eggs. Make a well in the dry ingredients, and pour in the wet mixture along with the blueberries. Use a cutlery knife to stir the dry into the wet until everything just starts to come together into a dough, then gently knead the mixture with your hands and bring it into a ball of dough. Put the ball on a lightly floured worksurface and pat into a 2½cm-thick disc. Use a 7cm round cutter to stamp out as many scones as you can, and put them on the prepared tray.