In a large bowl, beat the butter and salt until smooth and fluffy. Sift in the icing sugar and beat until smooth and combined.
Next, sift in the flour and beat until combined. It is easier to add half of the flour at a time, mixing thoroughly between additions. Once the flour is completely combined, shape the dough into two discs and wrap each disc in plastic wrap. Place the discs in the fridge for 30 minutes to allow the dough to cool and for the gluten to relax.
Preheat the oven to 350 degrees F and arrange your oven baking racks so that they are near the top of the oven. Roll out each disc of dough on a lightly-floured surface. Using a lightly floured cookie cutter, cut out the cookies into shapes. Place them onto parchment-lined baking sheets, abut 2-3 cm apart.
You can bake these cookies as is, or decorate them with sprinkles as I did. I recommend to gently press the sprinkles down into the cookies so that they don't fall off after baking. Bake the cookies for 15-18 minutes, or until the bottoms are golden brown.
Let the cookies cool on the baking tray for 5 minutes before transferring to a wire rack to cool. Enjoy!