HEAT oven to 325°F. Mix flour, baking powder and salt; set aside. Beat butter and sugar in large bowl with mixer 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 14x2-inch log with lightly floured hands. Place on greased baking sheet.
BAKE 25 to 30 min. or until lightly browned. Transfer to cutting board; cool 10 min. Use serrated knife to diagonally cut each log into 12 slices; place upright on baking sheet. Bake 15 to 18 min. or until slightly dried. Cool on wire racks.
MELT semi-sweet chocolate. Dip biscotti in chocolate; let stand until firm.