Start by making the jam. Place the frozen blueberries and 2 tbsp sugar in a saucepan and cook down for 10-15 minutes until thick and glossy. Meanwhile, make the scones by mixing together the flour, oats, sugar, milk powder and lemon zest. Next, rub in the margarine to form a crumb and stir in enough water until the mixture forms a soft dough. Roll out thickly with a little extra flour and cut into rounds. Place on to a lined baking sheet, brush the tops with the beaten egg and bake in the oven at 220`c for 12-15 minutes. Meanwhile, whip the double cream with the vanilla to stiff peaks. When the scones are baked, serve with the whipped cream and blueberry jam.