• Coat a baking dish with cooking spray and line with parchment paper.
• In a large bowl, toss together popcorn, pretzels and nuts

To make the caramel

• In a medium saucepan, bring sugar and 1/2 cup water to a rolling boil over medium-high heat
• Cook until mixture is amber in color, approx. 12 minutes
• Remove saucepan from heat and slowly fold in cream (mixture will sputter so be careful)
• Immediately add marshmallows and stir until melted

To make the popcorn mixture

• Pour caramel mixture over popcorn and pretzels and quickly stir with a rubber spatula to coat well
• Transfer mixture to the prepared pan. Sprinkle with coarse salt if preferred
• Spray a piece of plastic wrap with cooking spray then to press evenly into the pan
• Let cool or transfer to fridge for 30 minutes before cutting into bars using a sharp knife dipped in warm water.