Melt 3 tablespoons of butter in a large saucepan over low heat. Add 10 ounces of marshmallows, stirring until completely melted and smooth. Remove from heat and add 6 cups of Rice Krispies cereal, mixing well. Spread into a greased 9x13 inch pan and press down firmly for about 10 minutes to cool and set.

Use an egg-shaped cookie cutter to cut out egg shapes from the set treat or mold the mixture by hand. Place on parchment paper to prevent sticking.

In a mixing bowl, combine 4 cups of powdered sugar and 3 tablespoons of meringue powder. Gradually add 5-6 tablespoons of water while mixing. Continue mixing until smooth and stiff peaks form.

Divide royal icing into bowls and dye each with food colorings to achieve your desired pastel shades. Cover with a damp cloth to prevent drying.

Transfer colored icing into squeeze bottles and decorate the Rice Krispies Easter Eggs with patterns and colors. Add edible glitter or sprinkles while icing is wet.

Let decorated eggs sit at room temperature for 2-3 hours until icing is completely dry and hard.