What to bake this weekend: Gluten-free millionaire’s shortbread

For the base

• 100g unsalted butter, plus extra for greasing
• 100g ground almonds
• 100g brown rice flour
• 35g icing sugar
• ½ tsp xanthan gum
• large pinch of salt

For the caramel

• 100g unsalted butter
• ½  tsp salt
• 300g condensed milk
• 1 tsp treacle

For the topping

• 125g milk chocolate, broken into pieces
• 2 pinches of sea salt

Method

1. Preheat the oven to 150ºC/300ºF/gas mark 2. Lightly grease a 20cm square loose-bottomed brownie tin with butter.
2. To make the base, melt the butter in a saucepan, then stir in the remaining ingredients. Using the back of a metal spoon, press the mixture into the tin and smooth the surface. Prick all over with a fork and bake for 25 minutes. Leave to cool in the tin.
3. To make the caramel, melt the butter in a saucepan over a medium heat, add the salt and gradually pour in the condensed milk. Increase the heat to medium-high and stir continuously until the mixture starts to boil. Stir briskly for a few minutes until the mixture is thick and golden brown. Remove the pan from the heat and stir in the treacle. Stir well again and immediately pour over the cooled shortbread and smooth out using a spatula. Set aside to cool completely.
4. Melt the chocolate in a small heatproof bowl set over a pan of simmering water, making sure the base of the bowl does not touch the water. Alternatively, melt in a microwave on a low heat. Spread the chocolate evenly across the caramel, then sprinkle over the sea salt and leave to set.
5. Cut into 16 squares with a sharp knife, then carefully remove from the tin.