Place all cereal in a large mixing bowl and set aside. Butter a 13x9x2" pan and set aside.
In a medium saucepan, melt the butter over medium heat. Reduce the heat to low and add the marshmallows. Stir until the marshmallows are completely melted and smooth. Add the pudding mix and stir until completely blended.
Remove from heat and add 1/4 cup of the caramel and vanilla - stir until completely incorporated.
Pour the marshmallow mixture over the cereal and fold together until the cereal is completely coated. Pour the cereal mixture into the prepared pan. Spread out and press firmly into corners. Let cool. Drizzle remaining caramel over cereal. Cut into squares.
Best when served same day. Will keep up to two days in airtight container.