Preheat your oven to 180°C and grease and line a 20cm square springform baking tray.
Add your dairy free butter, light brown sugar and granulated sugar to a large mixing bowl and whisk with an electric whisk until light and fluffy.
Add your egg and continue to whisk. Add your vanilla extract and whisk again.
Add your flour, xanthan gum, cornflour and sea salt and mix well to form a dough.
Fold in the dairy free chocolate chips.
Transfer the mixture to your prepared baking tray, ensuring it's pressed into all the corners. Bake for 20-25 minutes, until golden brown on the top. Mine took around 22 minutes.
Remove from the oven and leave to completely cool in the tin while you make the caramel layer.