Preheat oven to 325°F. Mix flour, baking powder and salt; set aside. Beat butter and sugar in large bowl with electric mixer on medium speed until light and fluffy. Blend in eggs and vanilla. Gradually add flour mixture, beating well after each addition. Stir in cereal and white chocolate. Divide dough in half. Shape each half into 14×2-inch log with lightly floured hands; place on greased baking sheet.
Bake 25 to 30 min. or until lightly browned. Remove from baking sheet. Place on cutting board; cool 10 min. Using a serrated knife, diagonally cut each log into 12 slices; place upright on baking sheet, 1/2 inch apart. Bake an additional 15 to 18 min. or until slightly dried. Remove from baking sheet. Cool on wire racks.
Dip biscotti in melted semi-sweet chocolate. (Or drizzle chocolate over biscotti.) Let stand until set. Store in tightly covered container at room temperature.