Preheat the oven to 160℃/320℉. Prepare your baking tray with baking paper.
Add butter and powdered sugar to a large bowl and mix until fully combined.
Add flour and salt (see notes). Mix until fully combined and you are left with a smooth dough. Note: If the butter-sugar mixture is slightly cold before adding in the flour then I'd recommend you mix until the dough is just combined and then tip it on to a clean working surface and continue combining it with your hands (as seen in the video). If the butter-sugar mixture is room temp then it should combine very quickly in the bowl so no need to tip on to a surface.
If you'd like to add chopped nuts, chocolate chips etc. then add it to the dough prior to shaping.
Once the dough is fully combined, you can roll out the dough and use a cookie cutter or shape the dough into a log form and section with a knife. I then place each ball on the prepared baking sheet, place a small piece of baking paper on top and press down using a masher (I just like how the edges look once baked). But you can use anything to flatten them e.g. your palms, a mug, a fork or anything that makes a cute shape or indentation. It really doesn't matter, just know that they don't spread much during the baking process so the thickness/shape will be similar once they've baked.
Bake for 20-25 minutes at 160℃/320℉. I prefer a toastier biscuit so I bake it for 25minutes but if you prefer it paler then aim for 20minutes in the oven.