Fiona Cairns' blackberry and apple crumble cake is perfect for summer

STEP 2: Make the crumble topping first: in a large bowl, rub the butter, flour, sugar and cinnamon together into fine crumbs with your fingertips (if this is over-mixed in a food mixer, it quickly turns to biscuit dough). STEP 3: For the cake, sift the flour, baking powder, salt, ginger and cinnamon into a large bowl. STEP 4: In another large bowl, using a hand-held electric whisk, or in a food mixer, beat the sugar, cooled melted butter, eggs and vanilla until thick and creamy; this will take a few minutes on high speed. STEP 5: Spoon the batter into the prepared tin, then scatter the apples and blackberries over the surface and gently push them in.