Ok - so Christmas is over but I made these cookies a while back and the technique is what is important here: Royal Icing. That is how you get those smooth, beautiful designs on cookies. It dries quite hard so the designs stay, but it is still soft enough to eat. A quick google search will bring up many recipes. Look for ones that use pasteurized egg whites vs. meringue powder, such as Alton Brown's. You can use different extracts for flavor. Also, powdered or gel food coloring is best.
Adjust the thickness of the recipe with water. Add more for an even spread such as in the solid green cookies above. Leave out water for a thicker consistency and more control for detailed work, such as the dots on the cookie on the far right. The one on the bottom with the blue dot right in the middle of the cookie had too much water in the blue icing and the dot became more of a blob.
It was really fun and easy to work with. The icing is very forgiving. I also used silver edible beads to decorate.
I think I will be making some heart-shaped cookies come February!