In a large bowl add your flour, sugar and salt and mix well.
Mix the shortbread base as per recipe. Then press the shortbread into a pan evenly. prick holes in the shortbread before you bake to let out the moisture in the shortbread dough so it cooks evenly and crispy) and bake in the oven for 10 – 15 minutes until lightly brown.
While the crust is cooling, mix the brown sugar, egg and vanilla until smooth.
Then add the chopped walnuts into this mixture.
Pour this topping over the cooled baked shortbread evenly and place in the oven to cook.
Bake for about 25 minutes until the top has set. It should rise slightly.
Leave to cool before cutting into squares or bars or as you require them to be.