►Preheat oven to 375°F with rack in middle.
►In a large mixing bowl combine flour, baking powder, sugar, salt, pepper, and rosemary. Whisk to combine and remove any lumps.
►Add butter and gently work it into the flour with your hands, pinching it into pea-sized bits. Add Roquefort and gently combine by tossing it with your hands and breaking up any big chunks. It should remain in little crumbles but get coated with flour.
►Add cream and sour cream or yogurt and mix just until the dough holds together. It will be shaggy and slightly uneven in texture.
►On a well-floured surface, form dough into a disc 8 inches in diameter. It will be about 1½ inches thick. Then slice it into 8 wedges, like slicing a cake.
►Arrange the scones on a parchment lined sheet pan, spacing out evenly. Brush the tops with the beaten egg and finish with a little flaky salt if using.
►Bake until golden brown, about 35 minutes. Allow to cool slightly before enjoying.