Preheat oven to 180°C. Grease a baking sheet with oil. Combine sugar granules and two tablespoons of water in a pan and bring it to a boil.
Cook, stirring all the time, until the mixture is deep brown in colour. Set it aside and keep it warm on a pan of hot water. Combine chocolate and butter in a pan.
To melt this mixture, put some water in a bigger vessel and place the bowl with the chocolate in it and cook till it is smooth and even. Remove from heat and allow to cool. Beat eggs with vanilla essence until frothy.
Gradually add powdered sugar, beating well till all the sugar has been used up. Sift refined flour, baking powder and salt. Add to the egg mixture, little at a time, folding into it carefully and lightly without losing much aeration.
Blend in the cooled chocolate mixture. Spread half of this batter onto a prepared baking sheet. Bake for around six minutes. Remove from the oven and spread caramel carefully over the baked layer.
Sprinkle the chocolate chips. Stir in walnuts into the remaining chocolate batter and spread over the caramel layer. Bake for twenty minutes.
Take it out of the oven and cool on a wire rack. Refrigerate before cutting into bars or squares.