Line a 9×9 baking pan with parchment paper and spray it with baking spray.

In a large pot, melt butter over medium heat. Once melted, stir in vanilla extract and mini marshmallows. Reduce the heat to medium-low.

Stir the marshmallows continuously as they melt to prevent them from burning. Once fully melted, remove the pot from the heat and mix in the rice krispie cereal, additional marshmallows, and other other additives and mix until everything is well combined.

Transfer the mixture to the prepared baking pan and press it down into an even layer.

Let the treats cool at room temperature or in the fridge until they have firmed up. Once firm, slice them into squares and enjoy!