Preheat the oven to 180°C/160°C fan/350°F/Gas 4.

For the biscuits, in the bowl of a stand mixer fitted with a beater, beat the butter, caster sugar and light soft brown sugar together until light and creamy. Add the golden syrup and mix together.

Tip the plain flour, wholemeal flour, jumbo porridge oats and bicarbonate of soda into a large bowl and whisk together with a balloon whisk until the bicarbonate of soda and salt are evenly distributed.

Add the flour and oat mixture to the butter and mix on low speed to form a dough.

Turn the dough out onto a lightly floured surface and roll out to a rectangle measuring 35cm x 25cm. Using a 7cm cutter, stamp out 12 rounds. Place on a lined baking sheet, evenly spaced apart.

Bake for 12 – 15 minutes until golden, then remove from the oven and if the biscuits have spread, manipulate or cut the them while they are still warm to 7cm rounds, to fit the silicone mould. Leave to crisp up on the baking trays for 5 mins, then transfer to a wire rack and leave to cool completely.

For the caramel, tip the caster sugar into a pan and heat over a low heat until the sugar begins to melt, shaking the pan from time to time (do not stir). Bring to the boil, then cook to a dark amber caramel colour. Meanwhile warm the cream in a small pan.

Carefully remove the pan from the heat and stir in the warm (not boiling) cream. Return the pan to the heat and boil to 120°C/248°F. Remove from the heat and carefully stir in the butter until emulsified.

Spoon ½ tablespoon of the caramel into each of the silicon moulds and place a biscuit (base side down) on top of the caramel. Press down gently until the biscuit is touching the caramel then repeat with the remaining 11 biscuits. Leave to cool for 10 minutes, then freeze until firm. Pop the caramel biscuit out of the moulds.

For the chocolate coating, melt the dark, white and caramel chocolate either in the microwave or in bowls set over pans of gently simmering water until smooth. Spoon the white chocolate into a piping bag and one third of the dark chocolate into a separate piping bag. Carefully snip the tips off the piping bags to a fine writing point.

Using the remaining dark chocolate, coat 6 of the biscuits in the chocolate, then pipe 5 lines of white chocolate across each biscuit evenly spaced apart. Using a cocktail stick, feather the white chocolate.

Use the caramel chocolate to coat the remaining 6 biscuits, then pipe 5 lines of dark chocolate across each biscuit, evenly spaced apart. Using a cocktail stick, feather the dark chocolate.

Leave to set, then serve.