Line your baking dish with parchment paper, leaving some overhang for easy removal.
Place the digestive biscuits in a large bowl and roughly crush them into uneven chunks—this adds a rustic texture to the bars.
In a microwave-safe bowl, melt the dark chocolate and butter together in short 30-second bursts, stirring each time until smooth and glossy—your kitchen will fill with a rich, chocolaty aroma.
Pour the melted chocolate mixture over the crushed biscuits, then gently fold with a spatula until all the biscuit pieces are coated evenly with the shiny chocolate—this mixture should feel thick and sticky.
Transfer the mixture into the prepared dish, pressing down firmly with the back of a spatula or a small glass to create an even, compact layer—this step helps the bars hold together well.
Optional: sprinkle chopped nuts, dried fruits, or a pinch of sea salt over the top, then press them gently into the surface for added crunch and flavor.
Cover the dish with plastic wrap or a lid and refrigerate for at least 2 hours, allowing the mixture to set and develop a glossy, firm finish.
Once set, lift the bars out of the dish using the overhanging parchment paper and place on a cutting board.
Use a sharp knife dipped in hot water to slice into neat rectangles or squares, pressing down firmly to get clean edges.
Serve immediately or store in an airtight container in the fridge for up to a week; enjoy the rich, fudgy texture with a glossy finish.
