Break the biscuits into small chunks, keeping a mix of crumbs and larger pieces for texture

In a bowl, beat the butter, sugar, and salt until the mixture becomes light, creamy, and smooth

Melt the chopped chocolate gently over a double boiler or in short microwave bursts until glossy and smooth

Stir the melted chocolate into the butter mixture until fully combined and silky

Fold the biscuit pieces into the chocolate mixture, making sure every piece is well coated

Transfer the mixture into the prepared tin and press it down firmly to remove any air gaps and create an even layer

Chill in the refrigerator for about 3–4 hours until the mixture is fully set and firm

Remove the cake from the tin and place it on a rack

Melt the coating chocolate until smooth and pour it evenly over the top, letting it drip slightly down the sides

Smooth the surface with a spatula and allow it to set at room temperature until the coating is firm

Slice into portions once set, noticing the clean layers of biscuit and chocolate