1. Using eletric mixer, beat butter, sugar, vanilla.
  2. Slowly add flour and salt.
  3. Beat in sweetened condensed milk.
  4. Mix in chocolate chips.
  5. Spread mixture onto 9x13" pan. Greased spatula or wet hands make this easier. Refrigerate.
  6. Combine topping chocolate and butter and microwave until just melted.
  7. Spread melted chocolate over dough and refrigerate.
  8. After ~30 minutes, score the chocolate into small squares.
  9. Break into squares after ~4 hours.

Original Recipe