Combine butter and peanut butter. Add sugar and baking soda, beat well. Then stir in cornflakes and flour.
Reserve 1 3/4 cups of this crumb mixture.
Stir egg into remaining mixture then pour into a parchment lined baking sheet, pressing firmly to create a crust. Bake at 350ºF for 15 minutes.
Combine reserved crust mixture and chopped candy bars, set aside.
Spread the sweetened condensed milk over the baked crust, then sprinkle the candy bar mixture on top. Bake 25 minutes or until golden.
Cool, then cut into bars.