Preheat oven to 325°. Line cookie sheet with parchment paper.
Combine flour, baking powder and salt and set aside. In a large bowl, beat butter and sugars until light and creamy. Add eggs, one at a time, beating well after each addition, then beat in vanilla. Reduce speed to low then gradually add flour mixture until blended. Scrape bowl, then stir in walnuts and chocolate chips.
Divide dough in half. Shape each half into a 1-1/2-inch log on cookie sheet about three inches apart. Dough will spread to about 4 inches wide while baking. Bake 30-35 minutes, until golden brown. Let cool on the baking pan for five minutes.
Cut each log crosswise into 1/2-inch-thick slices. Place cut side down on cookie sheet and bake again for 20-25 minutes until golden brown and crisp. Cool on wire rack.