Spray a 13x9x2 inch baking pan with nonstick cooking spray (for baking) or grease the baking sheet.
In a large bowl combine the cereal, peanuts, toffee bits.
In a microwave safe bowl melt the marshmallows and butter. Stir every 25 seconds until completely melted.
Stir in vanilla.
Pour over the cereal mixture and gently stir until evenly coated.
Press into the prepared baking sheet.
In another microwave safe bowl add the caramel and water and microwave on high stirring every 25 seconds until smooth.
Drizzle over cereal mixture.
Melt white chocolate pieces and shortening together in a microwave safe bowl.
Stir every 15 seconds.
Drizzle over cereal mixture.
Allow to stand for 30 minutes or until set.
Cut into bar shape pieces and store in an airtight container layered between sheets of waxed paper.