Heat oven to 350°F. Line 13x9-inch pan with foil, extending foil over sides of pan. Grease foil. Lightly spoon flour into measuring cup; level off. In large bowl, combine flour, baking powder, baking soda and salt; mix well.
In separate large bowl, combine brown sugar, sugar and butter; beat until light and fluffy. Add eggs 1 at a time, beating well after each addition. Add vanilla; blend well. Gradually add flour mixture; blend at low speed just until combined. Fold in cranberries, walnuts and 1 1/2 cups of the vanilla chips. (Reserve remaining chips for topping). Spread batter in greased foil-lined pan.
Bake at 350°F. for 30 to 40 minutes or until golden brown.
In small saucepan over low heat, melt reserved 1/2 cup vanilla chips and shortening, stirring occasionally. Drizzle over warm bars. Cool completely. Cut into bars.