In a large bowl, cream together butter & sugars, until smooth. Beat in egg, until well blended. Mix in 1 tsp. orange zest and 2 Tbs. orange juice. Combine next three items; stir into the orange mixture. Mix in cranberries, and if using, walnuts, until evenly distributed. Drop dough by rounded tablespoons onto ungreased cookie sheets. Cookies should be spaced at least 2 inches apart.
Bake for about 12 minutes, in the reheated oven, until edges are golden. Remove from cookie sheets to cool on wire racks.
In a small bowl, mix together 1/2 tsp. orange zest, 3 Tbs. orange juice, and confectioners' sugar, until smooth. Spread over tops of cooled cookies or drizzle over them. Let stand, until set. Makes 48 (4 dozen) cookies.
Nutrition: One cookie 110 cal, 4.8 g fat (2.5 g sat), 15 mg chol, 67 mg sod, 25 mg pot, 16.2 carb, 0.5 g fiber, 1.1 g protein.