Place a large non-stick pan over low to medium heat. Add the butter and allow it to melt slowly, stirring gently until fully melted and smooth.
Add the mini marshmallows to the melted butter. Stir continuously over low heat until the marshmallows are completely melted and the mixture is smooth and creamy with no lumps.
Remove the pan from heat immediately once the marshmallows are melted. This prevents overheating and keeps the texture soft.
Add the Rice Krispies cereal to the melted mixture. Gently fold the cereal in using a spatula until all pieces are evenly coated. Avoid pressing or crushing the cereal while mixing.
Let the mixture cool slightly for about one to two minutes. This step helps keep the chocolate chips from melting too much in the next step.
Add the chocolate chips and extra mini marshmallows. Fold them gently into the mixture so they are evenly spread without fully melting.
Prepare a square pan by lining it with parchment paper or lightly greasing it. Transfer the mixture into the pan and spread it evenly.
Gently press the mixture into the pan using a spatula or lightly greased hands. Do not press too firmly to keep the treats soft and chewy.
Sprinkle crushed graham crackers and additional marshmallows on top. Lightly press them so they stick to the surface.
Allow the treats to cool at room temperature for 20 to 30 minutes until set.
Remove from the pan, cut into squares, and serve.
