Place brown sugar, corn syrup and peanut butter into a small saucepan over medium heat. Stir and let boil for one minute. Remove and stir in vanilla and salt. Pour over cereal mixture, stirring until well combined, the marshmallows will melt while stirring. Pour cereal mixture into prepared baking dish spreading and pressing evenly, will be sticky, doesn’t have to be perfect. Drizzle top layer with melted white chocolate then with melted chocolate.