Line a 9x13 inch baking dish with wax paper or parchment paper for easy cleanup, or grease with non-stick cooking spray to prevent sticking. Set aside.
In a large pot or medium saucepan, melt the butter over medium-low heat.
3 tbsp butter
Once the butter is melted, add the 3 cups of mini marshmallows.
3 cups mini marshmallows
Stir continuously. Once completely melted, remove the saucepan from the stovetop.
Add the rice krispies and sprinkles. Stir well to combine everything thoroughly.
6 cups rice krispies cereal, Easter sprinkles
Transfer the rice krispie mixture to the prepared baking dish and spread out evenly using a wooden spoon or rubber spatula.
Add the Easter sprinkles and peanut M&Ms on top and gently press them into the rice krispies mixture.
1 cup Easter peanut M&Ms, Easter sprinkles
Allow to cool completely at room temperature until the mixture becomes firm and holds its shape.
Once fully cooled, use a sharp knife to cut it into 24 bars or squares.
Arrange the M&M rice krispies treats on a platter or board and serve. Enjoy!