Pre-heat the oven to 175C (155C fan forced)

Line a baking sheet with baking paper and set aside.

Place the walnuts, flours, sugar, salt and baking powder in the bowl of a food processor.

Blitz until the nuts are broken into small pieces.

Add the butter and vanilla to the food processor.

Process until the mixture forms a dough. Take care not to over-process the dough.

Take tablespoons of the dough, rolling each spoonful into a ball.

Place the balls on the lined baking tray, leaving space between the cookies for spreading.

Now you need to make an indent in the centre of the cookie. I use the end of a wooden spoon handle, which I dip into the flour then press into the centre of the cookie. I like to make quite a deep indent which allows me to place more jam in the centre.

Use a teaspoon to drop jam into the indent, and gently press the jam into the hole with the end of the spoon.

Bake the cookies for 12 - 15 minutes, or until the cookies are golden and the jam is bubbling.

Remove the cookies from the oven, and allow to cool on the tray for 5 minutes. Don't skip this step or the cookies will fall apart as you try to transfer them to a cooling rack. Do not be tempted to eat the cookies at this stage as the jam is molten and can cause a nasty burn.

Once the cookies have cooled slightly, transfer them to a rack to cool completely.

Store in an airtight container.