Preheat oven to 180°C. Grease a 20 x 30cm baking tin.
In large bowl, combine the oats, flours, brown sugar and butter the mixture should resemble crumbs. Reserve 6 to 8 tablespoons of the oat mixture and press the remainder on the bottom of the prepared tin.
Bake in the preheated oven for 10 minutes.
Pour all of the condensed milk evenly over the baked base. Sprinkle the nuts and chocolate over the top. Finish off with the reserved oat mixture and press down firmly.
Bake for a further 25 minutes or until lightly browned. Cool completely before cutting into small squares or slices.