1

Preheat oven to 350°F. Grease two round 8 or 9-inch cake pans (use just one pan if you want extra-thick shortbread).

2

In a small bowl, whisk flour, cinnamon, and salt together; set aside. In a large bowl, with an electric mixer on low speed, cream butter, sugar and brown sugar together. Add vanilla extract. Gradually blend the flour mixture into the butter mixture. Press the dough evenly into the bottom of the pans.

3

Bake in the center of the oven for 20 to 25 minutes (2 pans) or 45 to 50 minutes (one pan).

4

The dough is brown, and is difficult to tell when it's done. The edges should be golden brown and the center should barely spring back when pressed. When you remove it from the oven, carefully score the shortbread into wedges. Cool completely, remove from the pan, and cut completely along the score lines.