Start by lining your 8x8-inch baking dish with parchment paper. This makes removing and cutting the bars a breeze.
In a large saucepan over low heat, melt together the chocolate chips, butter, and peanut butter. Stir continuously until silky smooth.
Once melted, remove the pan from heat and stir in the vanilla extract and sea salt. The salt balances the sweetness perfectly.
Fold the crispy rice cereal into the warm chocolate mixture until every bit is evenly coated. Work quickly before it firms up.
Gently stir in the mini marshmallows so they stay mostly intact. This creates gooey pockets inside every bite.
Pour the mixture into your prepared dish and press it down firmly with a spatula. For neater edges, use a second sheet of parchment to smooth the top.
Sprinkle a handful of mini marshmallows on top and lightly toast them with a kitchen torch for a beautiful, golden finish.
Refrigerate for at least 1 hour, or until completely firm. Once set, lift the block from the pan and slice into 12 even bars.
Your Chocolate Marshmallow Crunch Bars are ready to serve! Perfect for parties, potlucks, or late-night cravings.