Pop both bags of popcorn in microwave to package directions & combine in a large bowl - set aside

Combine butter, corn syrup, brown sugar, sweetened condensed milk & salt in a saucepan

Attach a candy thermometer to the side- don't let the tip touch the bottom of the pan- but make sure it's well within the liquid.

Heat over medium-high -stirring constantly until mixture boils

Once it boils reduce heat to medium & continue stirring until thermometer reaches 220 degrees

Remove from heat, carefully remove your thermometer & drizzle mixture over the popcorn

Fold with a spatula to coat the popcorn with caramel

Add in 1/2 the bag of peanut butter cups & continue to fold in - allowing them to melt a bit

Once the popcorn has cooled enough that it won't melt the peanut butter cups anymore- add in the remainder of your bag & mix until incorporated

Enjoy immediately