Place ingredients in mixing bowl. Blend with beater on slow speed until all ingredients are thoroughly combined. Do not over mix. Spread 300g (12oz) as crumble on separate tray. Bake at 180¡C (356¡F) for approximately 20 minutes. Pin remainder of mix firmly and evenly onto the base of the lightly greased baking tray. Bake base at 180¡C (356¡F) for approximately 20 minutes. Spread 850g hot caramel topping using Recipe No. R603a onto prebaked base. Sprinkle with baked crumble. Press into caramel with a rolling pin. Sprinkle crumble with chopped walnuts. Let caramel set then cut into desired shapes.
The metric recipe is of similar size to the avoirdupois recipe but is not an exact conversion.