Begin by greasing a 9x13-inch pan with a thin layer of butter and set it aside.

In a large saucepan over low to medium heat, melt 3 tablespoons of butter with 10 ounces of mini marshmallows, stirring until creamy and smooth.

Remove from heat and gently fold in 6 cups of crispy rice cereal until well coated.

Mix in 1 cup each of spring-colored M&Ms, candy-coated chocolate eggs, and a sprinkle of pastel sprinkles, folding gently to distribute.

Spoon the mixture into the prepared pan, pressing down evenly to compact and smooth the top.

Allow to cool at room temperature for 15 minutes, then refrigerate for at least 30 minutes until firm.

Once cooled, cut into squares and store in a tightly sealed container.