Begin by preparing a 9×13 pan. Line it with parchment paper, lightly mist with nonstick cooking spray, and set it aside.
In a large pot, melt one cup of salted butter. Stir continuously until the butter starts to brown slightly, giving off a delightful nutty aroma. Remove it from heat to prevent burning.
Immediately stir in two teaspoons of vanilla extract. Expect some bubbling as you stir for an additional thirty seconds until the sizzling subsides.
Add half of the mini marshmallows, mix until almost melted, then add the rest. Stir until all marshmallows are completely melted.
Gradually add Cocoa Krispies, 2 cups at a time, stirring lightly until combined. Keep adding until everything is evenly mixed.
Pour the mixture into the prepared pan. With lightly wet hands, gently push it to the edges. Be gentle to avoid crushing it!
For the chocolate garnish, microwave chocolate chips in a heatproof bowl for 30 seconds. Stir and repeat until completely melted. Let it cool for 3 minutes.
Using a spoon, drizzle the melted chocolate onto the treats or dip them. Sprinkle mini chocolate chips on top, and voilà – enjoy your delightful Cocoa Krispie Treats!