Cream the butter, then add the sugar and beat until it's fluffy.
Beat in the eggs and vanilla.
In a separate bowl, combine all the dry ingredients.
Stir the dry ingredients into the butter and sugar mixture. Mix together until well combined.
Divide the dough in half and wrap tightly in plastic wrap. Refrigerate the dough for a minimum of two hours or overnight.
Preheat your oven to 350 degrees (F).
Roll out the cookie dough to 1/4-inch thickness on a well-floured board.
Cut the dough with cookie cutters of your choice and place the unbaked cookies on an ungreased cookie tray (or line a baking sheet with parchment paper). If the dough gets sticky, add more flour to the board and/or rolling pin.
Chill the cutouts on the baking sheet for 10 minutes before baking. This will help keep them from spreading out and losing their shape.
Bake 6 - 10 minutes, basically until they're golden brown around the edges. They will brown quicker if the shapes are thinner.
Transfer the baked cookies to a wire rack and cool completely.
Once the cookies have cooled, frost with royal icing, either as prepared below or prepared on the icing box.
Beat all ingredients until icing forms peaks (7 minutes at medium-low speed with a heavy-duty mixer, 10 minutes at high speed with a hand-held mixer). If icing seems too thick, add more water 1/2 teaspoon at a time and beat in until desired consistency is reached.
*When measuring the flour firmly scoop and level the flour. If you have a scale, use 15 ounces of flour.
I often mix up cookie dough one day, refrigerate overnight, then bake the cutouts the following day. The cookies will keep in an airtight container for a few days, so I often decorate a day or two after baking them to spread out the work on decorated sugar cookies.
**Instead of making your own royal icing, you can purchase a boxed mix at your local craft store.
It is imperative that your bowls, spoons, spatulas, beaters and any thing else that comes in contact royal icing is grease free. I use Dawn Liquid Dish soap on these items because I know it will remove any trace of residual grease.
Cover the icing bowl with a damp paper towel or plastic wrap in between working with royal icing. It dries out quickly.
For longer storage, royal icing can be stored in a ziplock bag in the refrigerator for 3 days, or in the freezer for 3 months.