Line a 9x13 baking sheet with parchment paper, and coat with nonstick spray. Set aside.
Premeasure out all your ingredients (you want to work quickly with this recipe.)
In a large sauce pan, add the butter, salt, and melt it over medium heat.
Add in the marshmallows, and stir it all together until they are completely melted.
Remove the melted marshmallow mixture from the heat and stir in the vanilla extract.
Then stir in the cereal, and fold together till its completely and evenly coated.
Fold in 1/2 cup of the m&ms.
Transfer the mixture to the prepared baking dish. Use a piece of parchment paper to gently press it down evenly into the pan.
Sprinkle the remaining m&ms over the top, and some of the sprinkles and gently press them into the top.
Allow the rice krispie treats to set for 30 minutes, then slice them up.
Melt the candy melt colors in separate bowls. Melt them in 30 second increments, stirring between each until you can stir them smooth.
Drizzle the candy melts with a spoon (or by scooping them into a small ziplock bag and snipping the corner) over the top of each of the rice krispie treat squares.
Let the candy melts fully harden before serving the rice krispie treats.