Maltese Lemon Christmas Cookies

Combine the flour, baking soda, cream of tartar, and salt in a large bowl.
In the bowl of an electric mixer, cream the butter, sugar, vanilla, and lemon zest with an electric mixer until fluffy. Add the egg and continue mixing until well combined. Add the dry flour mixture to the butter mixture and mix until combined.
Scrape the dough onto a piece of plastic wrap, form a thick disc, wrap tightly, and freeze for 30 to 45 minutes, or until the dough is hard.
Preheat the oven to 350u0b0 F (180u0b0 C) (preferably convection setting). Line 2 (or more) baking sheets with parchment paper.
Once the dough is hard, brake 1/4 off the dough and keep the remaining dough wrapped in plastic wrap in the fridge. Lay a large piece of plastic wrap on the kitchen counter and cover generously with flour, lay the dough on top, dust with flour and cover with a second layer of plastic wrap. Roll the dough out thinly with a rolling pin. The dough is quite buttery; if it sticks to the cling film, dust it with more flour.
Dip cookie cutters in flour and cut out cookies.
Carefully transfer the cookies to the lined baking sheets, laying them with a bit of space in between, and decorate them generously with sprinkles. Continue with the remaining dough.
Bake for 6-7 minutes (slightly longer if using conventional) or until golden. Let the cookies cool completely on a wire rack.
Once the cookies are completely cool, store them in an airtight container for up to 1 week.