Whisk the flour, baking powder and salt in a small bowl.
Cream the butter and sugar using a mixer.
Add eggs to the butter/sugar one at a time.
Add vanilla and lemon zest.
Add the flour mixture to the dough and mix just until the ingredients are blended.
Divide the dough into 4 portions and shape each into a disc.
Wrap each disc in plastic film and chill for at least 3 hrs.
(You can also freeze the dough at this point, and then take it out as you need it.)
Roll out chilled disc on a flour-sprinkled countertop. Dough should be rolled out pretty thinly. Cut out the dough with your favorite cookie cutters and place cookies on silpat or lightly greased baking sheet.
Bake at 350 for 8+ minutes, depending on the size/thickness of your cookies.
Cool on wire rack.
Start with about 4 cups of powdered sugar in a bowl. Squeeze and strain the juice from a lemon and stir into the sugar. The consistency should be somewhat thick, so adjust the sugar/lemon juice accordingly.
I use baby food jars and pour/spoon the icing into as many jars as colors to be used. Add the gel color to each jar and stir--children love doing this.
I give each person. a rimmed cookie sheet to work on.
Use synthetic paint brushes of assorted sizes for painting the cookies.
And make sure to have lots of different sprinkles and sugars.
Allow cookies to air dry several hours before packaging.