PREHEAT oven to 325°F. Mix flour, baking powder and salt until well blended; set aside. Beat sugar and margarine in large bowl with electric mixer on medium speed until light and fluffy. Add eggs, bananas and vanilla; beat until well blended. Gradually add flour mixture, mixing until well blended after each addition. Stir in crushed cereal.

DIVIDE dough in half with floured hands; place on lightly floured surface. Roll each half into 14x3-inch log. Place, 2 inches apart, on nonstick baking sheet.

BAKE 25 to 30 min. or until lightly browned. Remove from baking sheet to wire rack; cool 5 min. Transfer to cutting board. Use serrated knife to diagonally cut each log into 12 slices. Place, cut-sides up and 1/2 inch apart, on same baking sheet. Bake an additional 12 to 15 min. or until slightly dry. Remove to wire racks; cool completely. Melt chocolate as directed on package; drizzle over biscotti. Let stand until chocolate is firm. Store in tightly covered container at room temperature.