Prepare the popcorn according to package directions or your preferred popping method. Allow it to cool.
Add the popcorn to a large mixing bowl, and remove any kernels.
Break the pretzel sticks roughly in half.
Add the pretzels, peanuts, and M&M's to the bowl with the popcorn. Toss to combine.
Place the white chocolate melting wafers in a microwave-safe bowl. Microwave in 30-second intervals, stirring between each interval, until completely melted and smooth.
Pour the melted white chocolate over the popcorn mixture. Gently stir until the ingredients are lightly coated.
Spread the mixture onto a parchment-lined baking sheet or large tray.
For extra pockets of white chocolate throughout the mix, drizzle any remaining melted white chocolate over the top before it sets.
While the white chocolate is still wet, lightly sprinkle flaky sea salt over the top.
Let the popcorn mix sit for about 30 minutes in a cool area, or refrigerate for 15 minutes, until the white chocolate has completely set.
Break the popcorn mixture into clusters. Leave some larger clumps for the best sweet-and-salty bites.
Serve immediately or store in an airtight container until ready to enjoy.
Notes
Mix-Ins: The measurements for the pretzels, peanuts, and M&M's are more of a guideline than a rule. Honestly, eyeball as much of the toppings as you'd like. I tend to load it up, so feel free to add a little extra of anything you love.