Put the flour, baking powder, mixed spice and butter into a bowl. Using your thumb and your fingers, pick up bits of the mixture, rub it together and then let it fall back into the bowl until the mixture resembles fine breadcrumbs. If you like, you can pop the mixture into the food processor and blitz until it resembles fine breadcrumbs.
If you have used a food processor, tip the mixture into a mixing bowl. Add the vanilla, sugar, and your choice of dried fruit to the mixture and stir together to combine using a wooden spoon. Then add the eggs and the egg white and mix again to form a fairly tight dough.
Using a large spoon or a mechanical ice-cream scoop, divide the mixture into twelve equal-sized blobs on the lined baking sheets. Sprinkle each one with a little extra brown sugar and then place them in the oven and
Once the rock buns are cooked, remove them from the oven and leave to cool completely on the baking sheets before serving.