1
: Pulse flour, cornstarch, icing sugar and salt together in food processor. Add butter and process until dough starts to come together. Press firmly into 13" x 9” (3.5 L) parchment paper-lined baking pan. Bake in preheated 350ºF (180ºC) oven for 5 minutes. Remove from oven.
2
: Pour sweetened condensed milk evenly over base. Sprinkle with peanut butter and chocolate chips. Bake an additional 20 minutes or until sides just begin to brown. Cool in pan on wire rack. Cut into bars.