Lightly grease the bottom of an 11x14 baking pan with cooking spray and line with parchment paper.

In a large pot over low heat, melt the butter and stir in the salt.

Set aside 1 ½ cups of mini marshmallows to mix in later. Add the remaining marshmallows to the melted butter and melt over low heat, stirring constantly. Remove the pot from the heat as soon as it is melted.

Immediately add the Rice Krispies cereal, the 1 ½ cups of mini marshmallows set aside earlier, 1 cup of the halved Reese’s peanut butter cup minis, ½ cup peanut butter chips, and ½ cup semisweet chocolate chips. Gently fold together until evenly combined.

Pour the mixture into the baking pan and spread it out evenly. Do not pack it too tightly!

Top with the remaining Reese’s peanut butter cups, peanut butter chips, and semisweet chocolate chips and gently press them into the bars to help them stick.

OPTIONAL: You can melt down some extra peanut butter chips and/or chocolate chips if you would like a drizzle on top!

Allow the Rice Krispie treats to cool in the pan on the counter for 30-45 minutes before cutting into bars.