Grease an 8x8 inch baking pan with butter or non-stick spray.
In a large pot, melt the butter over medium-low heat. Once melted add in the mini marshmallows and stir until melted fully.
¼ cup unsalted butter, 5 cups mini marshmallows
Remove the pot from the heat and stir in the vanilla extract and salt.
1 teaspoon vanilla extract, ¼ teaspoon salt
Add the Fruity Pebbles crispy rice cereal to the marshmallow mixture and stir until well-coated.
5 cups chocolate crispy rice cereal
Gently fold in the rest of the mini marshmallows while the mixture is still warm, so they melt slightly and create a marbled effect.
¼ cup mini marhsmallows
Press the mixture into the prepared baking pan using a spatula or wax paper. Press firmly to compact the mixture. Top with more chocolate chips and a sprinkle of sea salt then allow the treats to cool and set at room temperature for about 30 minutes before slicing into squares.
2 tablespoons white chocolate chips