Start by pre-heating your oven to 180c. Also grease and line a square 9 inch cake tin. Leave this aside.

In a pan, add the apples, sugar, cinnamon, vanilla and lemon juice. Give this a mix.

Place this onto medium heat, then cover and leave to cook just until the apples begin to soften. They should be tender when you poke them with a knife.

In a small bowl, mix together the corn flour and water. Pour this into your apple mixture and mix this in.

Cook until the mixture thickens. Then take this off the heat and leave aside.

In a pot, add the white chocolate and unsalted butter. Place this onto medium heat and heat until melted. You could also do this in a bowl, in your microwave. Once melted, leave aside to cool down slightly.

In a large bowl, add the eggs, sugar and vanilla. Whip these together until the mixture lightens in colour and increases in volume. This should take about 3 minutes.

Add the melted chocolate and butter mixture into this, whisk until combined. Now whisk in the flour and salt.

Add this into your prepared cake tin, then bake for around 40-45 minutes. It is done when a toothpick inserted into the centre comes out mostly clean, a few moist crumbs is fine.

Whiles the blondie is baking, make the crumble.

In a bowl, add all the ingredients for the crumble. Mix until clumps form, then leave aside until ready to use.

Once the blondie has baked, spread the apple filling over it, then add the crumble on top.

Place this back into your oven and bake again, for around 45-55 minutes. This time can vary, just keep an eye on it. It's done when the crumble looks brown and cripsy.

Once baked, leave to cool down at room temperature for about 20 minutes, then place this into your fridge to chill and set up for at least 2 hours. This gives your blondie layer time to fully set and it gives it a fudgy texture.

Place all the ingredients into a pan or pot. Heat over medium heat until melted. Leave this aside.

Once your blondie has chilled, take it out of the tin and cut it into pieces.

You want to serve them warm, so heat the pieces you want to eat in your microwave. Then serve with ice cream or whipped cream, and the sauce.