To make the apple filling, peel and core the apples, then chop into small chunks. Add to a pan on a low heat along with the light brown sugar, cornflour, cinnamon and mixed spice, and stir together
Cover with a pan lid, and cook the apple for 10-15 minutes until soft
Remove from the heat and leave to cool completely
To make the crumble topping, pre-heat your oven to 180C Fan/200C/375F/Gas Mark 5, and line a baking tray with baking paper
Put the plain flour, light brown soft sugar and cinnamon into a bowl and stir together
Add the butter and use your fingers to rub the butter into the dry ingredients until it resembles breadcrumbs. You can also use a fork to do this
Spread it out onto a lined baking tray and bake for 10-15 minutes until it is golden and feels firmer to the touch (it will firm up more as it cools)
Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line two 8" cake tins (that are at least 2" deep)
To make the cake, mix together the butter and sugar, ideally using an electric mixer, until smooth and fluffy
Add the eggs and milk, and whisk well
Then gently whisk in the self raising flour, cinnamon and mixed spice
Divide the mixture between the tins, use scales for accuracy if you like
Bake them for 35-40 minutes or until a thin skewer inserted in the middle comes out clean. Leave them to fully cool either in the tins or remove from the tin and place on cooling racks
Make the buttercream by mixing together the butter, cinnamon, icing sugar and milk, and mix until smooth. For best results do this with an electric whisk. If the buttercream is too stiff you can add a little more milk
If the cakes have domed on top, level them off with a cake leveller or a sharp knife
Put one of the sponges on your plate or cake stand and pipe small rosettes of buttercream around the edge
Then spread a thin layer of buttercream in the centre, and add half of the stewed apple mix over the top
Add the other sponge on top and pipe larger rosettes around the edge of the cake, and smaller ones in the centre
Fill the centre with the remaining stewed apple, and add the crumble topping all over the top of the cake - or wait and do this later if not serving immediately as it will go softer from being in contact with the buttercream after a little while
Store in an airtight container in a cool place, eat leftovers within 3 days