In the bowl of your electric mixer (or with a hand mixer), cream the butter and sugar, on medium speed until light and fluffy (about 3 minutes).
Add the eggs, vanilla and almond. Beat until combined. Add the salt and 3 cups of flour; beat until you have a smooth dough. If the dough is sticky (meaning when you touch it and pull your fingers away the dough sticks to you), add more flour a tablespoon at a time until it comes together. Divide the dough in half and wrap each half in plastic wrap. Refrigerate for about one hour or until firm enough to roll.
Preheat oven to 375°F. Line two baking sheets with parchment paper or silpat mats.
Remove half of the chilled dough from the refrigerator and, on a lightly floured surface, roll out the dough to a thickness of 3/8 inch. (Keep turning the dough as you roll, making sure the dough does not stick to the counter.)
Cut out shamrocks and circles for leprechauns using a lightly floured cookie cutter and transfer cookies to a baking sheet.
Bake the cookies for about 9-11 minutes (depending on size) or until the edges are just starting to have a hint of golden brown color around the bottom edge. Remove from the oven and let cookies cool on the baking sheet for 5 minutes before transferring to a wire rack to finish cooling.
Meanwhile, prepare the Best Ever Sugar Cookie Icing.
I separated the prepared icing into 4 clear bowls. Clear bowls as I can see the true color of the frosting. I put more into the green bowl as it is the color, I will use the most. White and yellow about ¼ cup and red just a little bit as I only use it for mouth.
I used Wilton food coloring gel. Green: Kelly Green, Red: Red no taste, Yellow: Lemon Yellow and for black I used Wilton Food Writer
Once you have the right green color, I then split it again. Reason is I will use a thicker frosting for the edge and thinner for the middle (flooding). The bowl for the flooding, I added 1 teaspoon of milk.
Once I have all the desire colors, I transfer them to piping bags with round decorating tips.
I first piped the edge of all cookies (I used the thicker green). By the time I am done doing all the edge and go back to the first one I am ready to do the flooding. 12. What flooding means is I take the thinner greed and fill up the center of my cookie inside the edge. To help the frosting spread evenly, I use a toothpick and gently push the frosting where it needs to go.
If you want to make dots, I used a thinner round decorating tip and slowly once you have the size of dot you want press down and it release the frosting.
Notes
I only take one disc out of the fridge at the time prior to roll. I have found out if the dough is cold, it rolls a lot better. If your house is warm, the dough will warm up rapidly, which means it will stick easier.When making sugar cookies, I prefer using a jelly roll pan (it has 4 sides) to a flat baking sheet (the cookies can slide off easily).Make sure the cookies are COMPLETELY cool before icing them.When coloring the frosting I use a toothpick from the gel jar to the frosting. Always making sure if I touch the frosting with the toothpick not to put it back in my coloring jar.