Use medium heat and melt butter slowly with marshmallows to prevent burning; Nutella is heat-sensitive, so add it only after the mixture cools slightly to preserve its chocolate-hazelnut flavor.

Toss the rice cereal in a separate bowl with a light coating of melted butter before mixing with the marshmallow mixture to ensure even, crunchy texture throughout.

Lightly butter your baking pan and line it with parchment paper, then butter the parchment—this prevents sticking and makes removal effortless without damaging your treats.

Dollop Nutella on top of the pressed mixture while still warm, then use a knife to create swirls before it sets completely for a professional marble effect.

Allow treats to cool for at least 2 hours at room temperature, then use a buttered or wet knife to cut clean squares without the mixture crumbling or sticking.