1. Preheat oven to 300 degrees. Grease 2 9 inch cake pans.

2. Place the sugar and orange zest in a bowl. Rub the zest in with your fingers. In the bowl of a mixer, cream together butter, sugar/orange mix, salt, and vanilla.

3. Chop chocolate. You want the pieces a little smaller than chocolate chips.

4. Beat the flour and the chocolate with the butter mixture, until well combined.

5. Divide the dough in half and press in prepared cake pans. Make sure each pan is even. Smooth the surface and prick the dough with a fork.

6. Bake for 40 minutes, until golden brown on the edges. Remove and loosen the edges with a knife.

7. Wait five minutes, then carefully place the shortbread out onto a clean work surface, all in one piece.

8. Using a pizza wheel or knife, cut into wedges. Do this while it is still warm so you can cut it. Transfer wedges to a cooling rack.