Heat the oven to 180C/160C fan/gas 4 and line a 20cm square tin with baking parchment, leaving some overhanging the sides. Put the butter, sugar, golden syrup and a small pinch of salt in a medium saucepan over a low heat and gently melt together, stirring to combine.

Pour in the oats and desiccated coconut, stirring to combine, then tip the mixture into the tin and smooth the surface using a spatula. Bake for 20-25 mins until golden and bubbling, then leave to cool completely in the tin.

Put the dark chocolate and 1 tbsp coconut oil in a heatproof bowl and melt in 20-second bursts in the microwave (or do this over a pan of simmering water, ensuring the bowl doesn’t touch the water). Repeat in a separate bowl with the white chocolate and 1 tsp coconut oil. Pour the melted dark chocolate over the cooled flapjack, smoothing it to the edges using a spatula. Drop the melted white chocolate over in spoonfuls and gently swirl it over the top to create a marbled effect. Chill until set, about 45 mins-1 hr.

Lift out of the tin in the parchment, then slice into 16 squares. Will keep in an airtight container for a week.