Makes 16 squares of Jammy Crumble Slice

Ingredients for base & crumble:

200g unsalted butter

1 3/4 cup plain flour

1/2 cup rolled oats

1/2 cup caster sugar

1/4 tsp salt

1/2 tsp baking powder

1 tsp vanilla extract

Method for base and crumble:

1. Preheat the oven to 180˚C. Line a slice baking tray tin with baking paper (I use 28x18cm).

2. Chop the butter into small cubes and place it in a microwave-safe bowl. Pop it in the microwave for 20 seconds, before removing it and giving it a good stir. If it hasn't completely melted return it to the microwave for another 15 seconds and then stir it again until melted.

3. Pour the melted butter, along with the other base/crumble ingredients into a large mixing bowl. Mix well to combine.

4. Reserve 2/3 cup of the crumble mixture and set aside. Add the remaining crumble mixture to the lined baking tray and use your hands to firmly and evenly press it down. This will form the base of the slice.

5. Place the slice base in the preheated oven to bake for 12-15 minutes, or until just starting to turn golden brown. Remove from the oven and set aside to cool slightly.

While the base is cooking, prepare your jam:

1. Add the cornflour into the water and stir to combine.

2. In a small saucepan over medium heat, combine all of the remaining ingredients for the jam (berries, lemon juice and caster sugar). Stir in the cornflour water.

3. Bring to a simmer and cook, stirring for 3-5 minutes or until thick and jammy.

4. Remove from the heat and allow to cool slightly.

Assemble the slice:

1. Once the base and jam have cooled slightly, scoop the jam on top of the slice base and use a palette knife (or the back of a spoon) to evenly spread it out, right to the edges.

2. Sprinkle the remaining 2/3 cup crumble mixture evenly over the top of the jam.

3. Return the slice to the oven to bake for 15-20 minutes, or until starting to golden.

4. Remove the tin from the oven and allow to cool before slicing into sixteenths (four rows of four).

5. Enjoy!