Chunky double chocolate cookies

1. Preheat oven to 350F.
2. Combine flour, baking powder and salt in medium bowl. Beat brown sugar, butter, and vanilla in large bowl with electric mixer at medium speed until light and fluffy. Add eggs; beat until well blended. Beat in melted chocolate. Gradually add flour mixture, beating well after each addition. Stir in white chocolate and nuts.
3. Drop dough by heaping tablespoonfuls 2 inches apart onto uncreased cookie sheets. Bake 11 to 12 minutes or until set. Cool on cookie sheets 1 minute. Remove to wire racks; cool completely. Store in tightly-covered container up to 1 week.