1. Start by lightly greasing a 12-cup muffin tin with oil or non-stick spray to ensure easy release later.
2. In a large pan over medium-low heat, melt the butter. Once melted, add the marshmallows and stir continuously until they’re fully melted and smooth.
3. Remove the pan from the heat and immediately mix in the Rice Krispies until every piece is evenly coated with the marshmallow mixture.
4. Spoon the mixture into each muffin cup, pressing down slightly with a lightly buttered teaspoon to shape them into neat nest forms and create a small indentation in the center for decorating.
5. Allow the nests to cool completely in the tin before gently removing them.

To Decorate:

1. In a small bowl, prepare a thick icing by mixing the powdered icing sugar with 2 teaspoons of water (adjust as needed to achieve the desired consistency). If you like, add a few drops of green food coloring to mimic grass.
2. Spoon a little of the icing into the center of each nest, then place mini egg candies into the indentation.
3. Top with a light sprinkle of extra festive sprinkles, and your nests are ready to serve!