Lorri's Cranberry Shortbread

adapted from Martha Stewart's Cookies book

1 cup (2 sticks) unsalted butter, room temperature
3/4 cup sifted confectioners' sugar
1 teaspoon pure vanilla extract
2 cups sifted all-purpose flour
1/2 teaspoon salt
1/2 cup finely chopped dried cranberries or cherries
zest of half an orange

Directions

1. Heat oven to 325 degrees.with a rack in center. Combine butter, confectioners’ sugar, vanilla, flour, zest, and salt in a large mixing bowl. Beat with a wooden spoon until combined but not too creamy. (I did it in my KitchenAide until the dough started to come together.) Stir in dried cranberries.
2. Pat dough evenly into an 8- or 9-inch-square baking pan. (Line with parchment paper for easy removal.) Bake until just beginning to turn golden, about 30 minutes. Place pan on cooling rack until cool enough to touch, about 20 minutes. Run knife around edges, remove shortbread, and transfer, right side up, to work surface.