• Softened at room temperature for about 45 minutes before you start making cookies. Whisk the flour and salt in a small bowl. Place the softened butter, sugar,and lemon zest on low speed until the sugar is incorporated. Raise the speed to medium and beat another 2-3 minutes until the color is lighter and fluffy . Cream on high speed until fluffy for about 4 minutes.
  
• Add the egg and vanilla and continue beating until just combined.
  
• Reduce the speed to low and gradually add in the flour mixture and beat until just combined
  
• 
• Transfer the dough to a sheet of plastic wrap and flatten into a thick disc. Wrap them up and refrigerate for at least 2 hours. I left mine overnight in the fridge
  

When ready to shape and bake:

• When ready to bake the cookies, remove the cookies from the fridge and let it sit at room temperature for about 10 minutes to soften a little bit. Preheat oven to 350 F (180 C) for conventional oven, 330 F (165 C) for convection oven, and position rack in the middle of the oven
• Set the dough on a lightly floured dough mat or a plastic wrap. Lightly flour the dough and your rolling pin. Cover the dough with a plastic wrap to prevent it from cracking when you roll it out. Roll it into about 1/4-inch thick. Use a cookie cutter dipped in flour, to cut it out into different shapes.
• I gather all the cut-out bits here and there and roll it out again and I manage to make few more cookies from that.
• Arrange on ungreased baking sheets, about 1-inch apart. Sprinkle with some decorating sugar and/or nonpareils. Lightly press them on the dough to make sure they adhere to the cookies later. Skip this step if you want to decorate with icing

Bake the cookies:

• I recommend baking one tray at a time. Keep the unbaked tray in the fridge while waiting for the oven. Bake in the oven for about 5 minutes and then rotate the pan and bake another 5 minutes. The cookies should be just lightly golden and the edges just deepened slightly in color.

Cool the cookies:

• Set the cookie sheet on a wire rack and use an offset spatula to lift the cookies onto another cooling rack and let them cool completely

Prepare the icing:

• Combine all the ingredients for icing and stir until smooth and to the consistency that is flowy but not too runny
• Divide into several portions if you plan to color them. Add the gel food coloring and stir to combine
• Transfer to a piping bag or plastic bag, cut off the tip and start icing the cookies. Add sprinkles on top if you want to before the icing hardened