In a bowl, sift together all purpose flour, baking powder and salt. Set aside.
Cream together butter (at room temperature) and confectioners sugar using paddle attachment of your stand mixer or hand mixer for 2-3 minutes.
Add egg and lemon and vanilla extract and mix.
Start adding the flour mixture slowly till all is well incorporated. You will know it is done when most of it comes together as a dough (sticks to the paddle).
Wrap the dough with plastic cling sheet and chill for 3-4 hours or overnight. .
Preheat the oven to 400 F degrees.
Roll the dough on floured surface to 1/4 inch thickness. Use more flour for dusting if the dough sticks to the floor.
Cut into shapes using cookie cutters.
Bake for 6-8 minutes at 400 F degrees. The cookies should be taken out just when the edges start to get brown.
Let them cool completely on wire rack before decorating. It's best to decorate the cookies the next day.