Prepare the Nougat Base: In a large saucepan, combine the butter, evaporated milk, granulated sugar, caster sugar, and corn syrup. Stir over medium heat until the sugars dissolve and the mixture begins to bubble gently. Continue to cook, stirring occasionally, until the mixture reaches a soft-ball stage (around 115°C on a sugar thermometer). It should look glossy and slightly thickened, with small bubbles breaking the surface.

Whip in the Peanut Butter and Vanilla: Remove the pan from the heat. Quickly stir in the peanut butter and vanilla extract until fully incorporated and the mixture takes on a creamy, uniform colour and texture. The aroma of peanuts and vanilla will fill your kitchen at this stage.

Fold in the Icing Sugar: Gradually add the sifted icing sugar, folding it in with a sturdy spatula until a thick, pliable nougat forms. This will be quite stiff and look like a dense dough. Press this nougat mixture evenly into a greased and lined 20x20cm square baking tin. Smooth the top with the back of a spoon or your hands, then place it in the fridge to chill for at least 30 minutes until firm to the touch.

Craft the Caramel Layer: In a separate medium saucepan, melt the caramel sweets with the double cream and a pinch of sea salt over low heat, stirring constantly. The caramel will become a beautiful amber colour, smooth and lusciously gooey. Once fully melted and combined, remove from the heat and stir in the chopped roasted peanuts.

Assemble the Layers: Retrieve the chilled nougat base from the fridge. Carefully pour the warm peanut caramel mixture over the nougat, spreading it evenly to the edges. The caramel will be wonderfully sticky and thick. Return the tin to the fridge for another 45-60 minutes, or until the caramel layer is firm enough to cut without sticking excessively.

Chocolate Coating: Once chilled, lift the block out of the tin using the parchment paper. Use a sharp, warm knife to cut it into 12-16 bars. Melt the chopped chocolate with the optional coconut oil in a heatproof bowl over a pan of simmering water (bain-marie) or in the microwave in 30-second intervals, stirring until smooth and shiny. The chocolate should be fluid and glossy, ready for dipping. Dip each bar into the melted chocolate, ensuring it's fully coated. Let any excess drip off, then place the coated bars on a parchment-lined tray. Allow the chocolate to set in the fridge for a final 15-20 minutes until hard and crisp.