Ingredients FOR THE CHOCOLATE MUD CAKE 113 g unsalted butter (1 stick / ½ cup) 75 g dark (70%) chocolate (2.6oz) 85 g plain (all-purp) flour (⅔ cup / 3oz) 20 g cocoa (2 tablespoons / 0.7oz) (notes) ½ teaspoon baking powder ¼ teaspoon salt ½ cup / packed light brown sugar (100g / 3.5oz) ⅓ cup white granulated sugar (65g / 2.3oz) 2 teaspoons instant coffee 2 tablespoons hot water (note 1) ¼ cup milk (60ml) 1 large egg 1 teaspoon vanilla extract FOR THE CHOCOLATE MOUSSE 2 ½ cups whipping cream, divided (625ml) 200 g dark (50%) chocolate (7oz) 57 g unsalted butter (½ stick / ¼ cup) 2 tablespoons icing sugar (note 1) CHOCOLATE GLAZE (OPTIONAL) ½ cup water 2 teaspoons powdered gelatine ½ cup cream (125ml) ¾ cup caster (superfine) sug