To toast walnuts:
Place nuts in a cold frypan. Turn heat to medium-low and stir nuts frequently as they heat. The nuts will start to smell fragrant when they begin to toast. Remove them from the heat - they will continue to toast slightly with the heat of the pan. Let cool and use in recipe.
Try adding 1-1/2 teaspoons / 7.5 ml orange zest to the topping.