Preheat the oven to 400.

Start by beating the butter until creamy. Then add the sugar and mix until just combined. Add the zest and juices and mix. Next, add the flour along with a beaten egg and mix until the dough begins to form clumps.

At this point, you can get your hands into it and bring the dough together (It may not seem like it will stay together, but just keep working at it until it does). Place on a floured surface and roll the dough out until it’s around a 1/4 inch in thickness. Using a 2 inch round cookie cutter, cut the dough and place on a parchment lined baking sheet. Chill for about 20 minutes to help stop spreading.

Bake for 8-10 minutes. 

Make the icing by mixing together butter, sugar, vanilla and milk. Make adjustments to get a smooth spreadable consistency.

Once cookies are cooled, ice and top with sprinkles.