Add the strawberries, lemon juice and sugar to a saucepan and place on a low heat. Bring to the boil and allow to boil steadily for 10-15 minutes until the jam is set. To test it, spoon out a tiny bit of the jam onto a cold plate and leave for a minute. If you can push it with your finger and it doesn't flood back, it's ready.

Once cooked, turn off the heat and leave to cool for around half an hour before you begin making the crumble.

Preheat the oven to 180'C / Fan 160'C / Gas Mark 4. Line a 20cm square tin with baking paper and set to one side.

Add the melted butter, caster sugar and flour to a large mixing bowl and stir until the mixture starts to come together. Use your hands to create a 'crumble' type texture - kind of like breadcrumbs but some big lumps are really good!

Take half of the mixture and press it down firmly with a spoon or your fingers into the lined baking tin so that it covers the bottom in an even layer.

Next spoon over the jam, spreading it evenly over the pressed-down crumble mix. Once the jam is spread, crumble over the rest of the mixture evenly and then place in the oven.

Bake for 35-40 minutes until the crumble is lightly golden on top and the fruit mixture is bubbling round the edges. Remove from the oven and cool completely before slicing into 16 squares.