I tried out a different toffee square recipe from a vintage cookbook. This is similar to the type of recipe that has a bottom cookie layer and a sweetened condensed milk baking on top with a few mix-ins. This one doesn't have any mix-ins, but it does have a fudge frosting on top. This cookie is a definite hit.
Ingredients for the cookie layer:
1/2 cup butter
1/2 cup sugar1/2 teaspoon salt