Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add pumpkinseeds; cook 4 minutes or until seeds begin to pop and lightly brown, stirring frequently. Remove from heat; cool.
Lightly coat a 13 x 9-inch baking dish with cooking spray; set aside. Melt butter in a large saucepan over medium heat. Stir in marshmallows; cook 2 minutes or until smooth, stirring constantly. Remove from heat; stir in vanilla and salt. Stir in reserved seeds, cereal, and cranberries. Scrape mixture into prepared dish using a rubber spatula.
Lightly coat hands with cooking spray; press cereal mixture evenly into prepared dish. Cool completely. Cut into 16 bars.