1 cup / 2 sticks unsalted butter at room temperature
1 cup white sugar
1 egg
1 tsp vanilla extract
1/2 tsp salt
3 cups flour
In a stand mixer, cream together butter and sugar until well incorporated. Add egg, salt, and extracts. Mix well. Preheat the oven at 375 degrees F. Sift the flour, then add it to the egg mixture, mixing a cupful at a time. After all the flour is well blended into the mixture, the dough should feel well formed and non-greasy.
Roll to 1/4 inch thickness between two sheets of parchment or wax paper, chill the dough for 30 minutes. Once the dough is well chilled, cut out shapes place them on a baking sheet. Freeze the sheet for 15 minutes. Bake at 375 for 7 to 9 minutes. The cookies will continue to cook in the heat of the sheet, so it is important to remove them promptly.
When you see the slightest brown edge on the cookies, take them out and let them cool for about 15 minutes. Remove them on to cooling rack to let them completely cool.
I would suggest decorating the cookies the next day. You can let the cookies sit out for a day on the cooling rack, or place them in an air tight box and freeze them for about 24 hours.
Icing for cookies
3 tbsp meringue powder
1/2 tbsp light corn syrup
1 tsp clear vanilla extract
1/2 cup water
1 lbs powdered sugar
Oil free icing colors
Ziploc or piping bags
The bowl you use to make the icing must be dry and free or grease or oil residue. Grease prevents the icing from coming together. Add meringue powder, light corn syrup, clear vanilla extract, and water.
Whisk until light and foamy. Sift the powdered sugar and gradually add it to the liquid mixture, a little at a time. Whisk the mixture until the powdered sugar is incorporated.
Now, beat mixture on medium-high for about 7 to 9 minutes. The mixture will thicken and form shiny peaks. The mixture is ready to use. You may store the icing in an airtight container at room temperature.
Use oil free colors to make colored icing of your choice. Pour them in ziploc bags or icing bags and pipe on cookies. You can pipe out borders first, and then flood the filling color with the back of a spoon. A good rule of thumb would be to use one color, let it dry, and top it with another color. Keep a damp paper towel handy to keep the icing tips moist so they don't dry out. Enjoy!