Prepare the peanut butter filling: In a small bowl, combine the peanut butter, icing sugar, and softened butter. Stir with a fork until the mixture becomes smooth and glossy, with no streaks of white icing sugar visible. The filling should feel thick but spreadable, like a soft dough.

Assemble the cracker sandwiches: Lay out 20 Ritz crackers on a clean work surface. Spoon about half a teaspoon of peanut butter filling onto each cracker. Spread it evenly to the edges — you'll know it's right when the filling reaches every ridged corner. Top with a second cracker and press gently until you hear a soft click as the crackers settle together.

Make the chocolate coating: Place the milk chocolate, dark chocolate, double cream, golden syrup, vanilla extract, and sea salt in a heatproof bowl set over a saucepan of simmering water. Stir slowly with a rubber spatula. After about 3-4 minutes, the chocolate will begin to melt, turning from solid lumps into a thick, dark river. Continue stirring until the mixture is completely smooth and glossy, with a rich, fragrant chocolate aroma filling your kitchen.

Dip the sandwiches: Remove the bowl from the heat. Using a fork, lower one cracker sandwich into the warm chocolate. Turn it gently to coat all sides. Lift it out and tap the fork against the bowl's edge — you'll hear three or four taps as excess chocolate drips back. The coating should look shiny and even, with no cracker peeking through.

Set the cookies: Transfer each dipped cookie to a baking tray lined with parchment paper. As you place them, the chocolate will slowly pool around the base, creating a neat, even edge. Leave about 2cm space between each cookie. Once all are dipped, place the tray in the refrigerator for at least 45 minutes, or until the chocolate feels firm to the touch and no longer leaves a mark when pressed gently.

Final check and storage: After chilling, the cookies should lift cleanly from the parchment paper. The chocolate will have a satisfying snap when you bite into it. Store in an airtight container in the fridge for up to one week — though my kids absolutely devour this every time I make it, so they rarely last that long.