In a stand mixer or with a hand mixer, beat together the butter, shortening and sugar until fluffy, about 2 minutes.
Now add the extracts and the zest and mix for another minute.
Add the salt and slowly sift in the two flours, beating as you add it, until you have a crumbly dough. Do not overbeat. You don't want to develop the gluten in the flour.
If the mixture doesn't hold together, sprinkle some water and mix, but be careful not to make a sticky batter.
Put the dough into a 9-inch baking dish (I used a glass one) and press down the dough into a smooth and even layer.
With a fork, make holes in the dough in a decorative pattern.
Place in a 300-degree oven and bake for 45-50 minutes or until the shortbread is just slightly darker at the edges.
Place on a rack to cool. When still slightly warm, take a sharp knife and cut into squares, going almost all the way through the dough.
Allow the shortbread to continue cooling. When completely cooled, cut all the way through the shortbread to separate the pieces.
If adding the candied pecan topping (recipe below), take out of the oven about 10 minutes before it is done, sprinkle the topping over the shortbread, and continue baking for the remaining time.
The remaining steps are the same.
Candied Pecan Topping