Step #2 Lightly butteran 18cm / 7 inch cake tin or a 23cm / 9 inch sandwich tin & line the base with parchment paper.
Step #3 To make the crumble topping, sieve the flour into a bowl & using your hands rub in the butter until it resembles breadcrumbs, then stir in the the sugar & cinnamon.
Step #4 Set aside.
Step #5 To make the cake, sieve the flour, cornflour, baking powder & salt into a bowl.
Step #6 Add the butter, sugar & eggs & beat together until smooth.
Step #7 Transfer to the prepared cake tin & level the top, then sprinkle it over the reserved crumble topping.
Step #8 Bake for 45 mins until firm & springy, remove this from the oven & leave to cool in the tin for 5 mins.
Step #9 Turn out onto a plate & cut into slices - serve this with creme fraiche / ice cream.