Spray the pan with nonstick cooking spray and set aside.
In a large mixing bowl, add 5 cups marshmallows and 3 tablespoons butter.
12 Tablespoons unsalted butter
Cook for 2 minutes or until the marshmallows have swollen to fill the bowl and the butter is mostly melted.
Remove the bowl and mix well. Add about ¼ teaspoon white gel food dye. This won’t make the mixture overly white, but it will definitely make it a little whiter and help offset the offwhite look. Mix well.
white gel food coloring
Add 4 cups rice cereal and mix until all the cereal is coated well.
16 cups rice cereal
Place the mixture in the pan and spread even until it makes a layer that covers the entire bottom of the pan. Using your hand or a flat bottom measuring cup, press the layer flat so it’s nice and tight.
Repeat steps 2-5 for the next layer but do it in black. If your black dye gives off a dark purple look rather than full black, add 3 drops or so of yellow food dye to make it pitch black.
black gel food coloring, yellow gel food coloring
Repeat steps 2-5 for another white layer and another black layer, ending with the fourth layer as black.
Sprinkle the top with white jimmy sprinkles. Cover and let rest for 2-4 hours or until set and able to be cut.
white jimmy sprinkles