Preheat oven to 350 degrees.

In medium bowl, cream butter and sugar, then add egg yolks and continue to mix well. Gradually add flour until well combined.

Roll dough into small balls, then wet in slightly beaten egg whites and then again in the crushed pecans.

Place cookie dough balls on baking sheet, then print thumb on cookies to create a dent in the center of each.

Bake 5 minutes, remove and print again with thumb, then bake additional 5 minutes.

Let cool completely before frosting.

FOR THE ICING:

Add butter, powdered sugar, vanilla extract, and milk to medium bowl, beat well until smooth consistency. Divide in two parts and add food coloring.

**IF YOU ARE USING THE ALL NATURAL FOOD COLORING listed below, replace the milk in the recipe with the "dyed" water - see below.

FOR THE NATURAL FOOD COLORING: I followed the instructions below from Real Mom Nutrition

For the red/pink food dye: Rinse, trim, and chop 2 beets. Place pieces in a blender or food processor and grind to a pulp. Combine pulp and 1 cup water in a saucepan and bring to a simmer. Continue to simmer for about 40 minutes, stirring occasionally. Set a strainer over a bowl. Pour mixture through strainer, pressing ground beets against the strainer to squeeze out all extra liquid. Use the liquid as a replacement for the milk in the frosting recipe above.

For the green food dye: In a blender, combine 3 cups spinach with 1/2 cup water, blend until smooth. Replace the water or milk in your frosting recipe with equal amount of the spinach mixture. Set a strainer over a bowl. Pour mixture through strainer to remove any "pulp" so you are left with the liquid only. Use the liquid in place of the milk in the frosting recipe.