Line a 9" x 13" pan with parchment paper, letting two opposite sides overhang the pan. Set aside.
In a very large pot over medium heat, melt the butter. Add 2 of the bags of marshmallows and stir almost constantly until they are completely melted. Stir in salt. Remove from heat and pour in Rice Krispies, folding gently the whole time until all is combined. Then gently fold in final bag of marshmallows so that these marshmallows stay whole.
Press mixture into the parchment paper lined pan to make a flat surface. I like to use the buttery side of the butter wrappers just used for the recipe - this helps you press in the mixture without sticking. Let cool completely. Then lift the bars out of the pan using the parchment paper overhangs. Cut into squares.
In a medium microwave-safe bowl, very gently melt the white chocolate on a lower heat seating in the microwave, stirring often. Take special care to not let the chocolate scorch, or it will be ruined. You could also melt the chocolate on the stovetop using a double boiler. Once chocolate is almost all melted, just continue to stir until it is completely melted. Remove chocolate from heat. Then stir in candy coloring, to your desired color.
Spoon and spread the colored chocolate over a couple individual bars, and then add sprinkles while chocolate is still warm and soft. Repeat, two bars at a time, until all bars are coated. Let chocolate set completely.
Nutrition information is automatically calculated by Spoonacular. I am not a nutritionist and cannot guarantee accuracy. If your health depends on nutrition information, please calculate again with your own favorite calculator.