Line a baking sheet with parchment paper or waxed paper.
In a large mixing bowl, stir together the cereal and marshmallows.
Place the white chocolate and peanut butter in a microwave-safe bowl. Heat at half-power in the microwave in 30-second increments until the chocolate melts when stirred. Add the vanilla and salt, and stir until smooth.
Pour the white chocolate mixture over the cereal mixture, and stir until evenly coated.
Drop the mixture by 2-tablespoon portions (A #30 cookie scoop works well.) onto the lined baking sheet. If you like, add sprinkles and/or mini chocolate chips to the top of each cookie.
Place the pan in the refrigerator, and chill until the cookies are set (about 30 minutes).
Notes
Store in an airtight container in the refrigerator up to a week, although best within the first few days.