For the toffee sauce, place the can condensed milk in a pan of water and simmer for 4 ½ hours (ensuring you keep the pan topped up), then leave to cool in a bowl of water so a toffee forms. Remove the caramelised milk from the can and melt with the butter and golden syrup together in a bain-marie

When melted, whisk together to form an emulsion then pass through a sieve. Chill in the fridge until needed - this will make around 650g

For the bases, blitz the digestives into fine crumbs. Melt the butter and mix with the digestives

Roll the mixture out between two sheets of silicon paper to fit a 20cm x 15cm tin or tray. Lower into the tray and press to the edges. Chill to set

To make the mousse, warm the toffee sauce until hot but not simmering, then add the gelatine, stirring until it has completely melted. Allow to cool to room temperature

Whip the double cream to soft peaks. Fold the cream into the toffee sauce and spread in a layer on top of the biscuit base. Chill in the fridge until set

For the chocolate jelly, bring the sugar and water to the boil, add the cocoa and simmer for 5 minutes. Remove the cocoa mix from the heat, add the gelatine and stir until it has dissolved

Allow the chocolate mixture to cool to room temperature then pour the jelly over the caramel mousse and leave to set

To plate cut into small squares and arrange on a plate with some extra cocoa powder for dusting. Serve