Prep time: 10 min.Baking time: 12 min.Decoration time: 30 min.Cooling time: 120 min.
Knead flour into cookie dough until smooth. Roll to a scant 1/4-inch thickness and cut cookie shapes using the printable template. Arrange cookies on 2 parchment-lined sheet pans.
Bake in a preheated 350-degree oven until golden, about 10-12 minutes. Cool completely.
Beat confectioner's sugar, egg white powder and warm water until fluffy, about 1 minute. Spoon 1 cup frosting into a resealable plastic bag fitted with a plain pastry tip. Thin remaining frosting with a few teaspoons of water until it resembles the texture of glue. Spoon into another resealable plastic bag.
Using thicker frosting, pipe the cookie's outline. Snip a small corner from the bag of thinner frosting. Use it to fill the inside of the cookie's outline. Sprinkle top with decorating sugar. Set aside to dry for 2 hours.
Using thicker frosting, pipe lacey lines on cookies. Dot with MY M&M'S® Brand Milk Chocolate Candies My Color™.