Beat butter and sugar in a 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 14x2 inch log, with lightly floured hands; place on greased baking sheet.
Bake 25-30 minutes or until lighty browned. Remove from baking sheet, place on cutting board; cool 10 minutes. Using a serrated knife, diagonally cut each log into 12 slices; place upright on baking sheet. 1/2 inch apart. Bake an additional 12-15 minutes or until slightly dried. Remove from baking sheet. Cool on wire racks.
Dip biscotti in melted semisweet chocolate. (or drizzle chocolate over biscotti). Let stand until set. Store in tightly covered container at room temperature.
VARIATION: Omit semisweet chocolate. Sprinkle cooled biscotti with icing sugar. Or drizzle with combined 1 cup icing sugar and 2 tablespoons orange juice. Let stand until set.