Preheat the oven to 180˚C (160˚C for fan assisted ovens)/ Gas Mark 4.
Mix the egg, oil, water and brownie mix gently together in a bowl until combined.
Pour the mixture into the greased and lined tin and gently level the surface.
Bake in the centre of the oven for 25-30 minutes, or until a knife inserted into the centre of the brownie, comes out clean. Leave to cool in the tin on a wire rack.
Place all the ingredients into a pan and heat gently until the butter has melted. Slowly bring the mixture to a gentle boil, stirring all the time then let the mixture boil for 8-10 minutes, until it thickens and turns a golden caramel colour. Keep stirring continuously to prevent the mixture from catching on the base of the pan.
Cool the caramel for 3-4 minutes then pour onto the cold brownie mixture. Leave in a cool place until completely cold and set. Spread the chocolate fudge icing over the set caramel and sprinkle over the chopped pecans. Chill in the fridge for at least 1 hour before lifting the slab of brownie out of the cake tin, peeling away the paper at the sides and cutting into 20 pieces.TIP Keep the brownies in the fridge until required then leave at room temperature for 30 minutes to soften slightly before serving.