Savory Herb Shortbread

1/2 cup chopped walnuts
2 oz. (1/2 cup) shredded fresh Parmesan cheese
2 oz. (1/2 cup) shredded sharp cheddar cheese
1/4 cup butter, cut into chunks
2/3 cup all purpose flour
1/2 teaspoon dried sage leaves
1/4 teaspoon dry mustard
1/4 teaspoon coarse ground black pepper

Heat oven to 350 degrees. Spread walnuts on small cookie sheet. Bake for 5-7 minutes or until golden brown, stirring occasionally. Cool 5 minutes or until completely cooled. Increase oven temperature to 425 degrees. In food processor bowl with metal blade, combine cheeses and butter. Process with on/off pulses until mixture is crumbly. Lightly spoon flour into measuring cup; level off. Add flour, cooled toasted walnuts and all remaining ingredients; process until dough forms. Divide dough into 4 equal parts. On lightly floured surface, pat or press each part into disk. Roll each to form 5-inch round. Cut each round into 6 wedges. Place on ungreased cookie sheet. Bake at 425 degrees for 6-8 minutes or until light golden brown around edges. Remove from cookie sheet; place on wire rack to cool.