Lightly grease a 9x13-inch baking dish or line it with parchment paper for easy removal later.
In a large pot, melt the 8 tablespoons of unsalted butter over low heat. Once melted, add in two bags of miniature marshmallows and stir continuously until they are completely melted and smooth. Add the kosher salt and mix well.
Remove the pot from the heat and gently fold in 9 cups of Rice Krispies cereal until evenly coated with the marshmallow mixture.
Fold in the remaining bag of miniature marshmallows for that extra marshmallow goodness.
In a microwave-safe bowl, melt the 3 bars of white chocolate in 30-second intervals, stirring in between until smooth. Add a few drops of the pink candy coloring and mix until you achieve your desired shade.
Pour the marshmallow mixture into the prepared baking dish. Use a greased spatula to gently spread it evenly. Drizzle the melted white chocolate over the top and use a knife or spatula to swirl it into the bars.
Sprinkle a generous amount of your favorite sprinkles over the top, pressing them gently into the mixture so they stick.
Allow the bars to cool at room temperature for at least 30 minutes, or until set. For quicker cooling, place them in the refrigerator for about 15 minutes.
Once set, lift the bars out of the dish using the parchment paper (if used) and cut them into squares. Enjoy your Extra-Marshmallow Rice Krispies Bars with Confetti!