Bake a box of brownies as directed. (Any kind. Whatever kind you want.)
2 c. chocolate chips
1 tablespoon butter
1 can sweetened condensed milk (I love this stuff!)
Spread melted stuff on warm brownies. Sprinkle with topping (nuts, assorted chips, candy pieces, whatever your heart desires) and marshmallows.
Bake at 350F until marshmallows are golden.
(The note at the bottom of my recipes says, "Tell your mom how much you love her." Then my Kaitlin added, "& your sister!"