Preheat oven to 300ish degrees. Cooking hotter and faster will make crispier cookies.
In a bowl, mix flour, sugar and salt together.
Add chunks of butter and mix with your fingers until it all comes together in a ball.
Dump on a flat surface and slap, roll, or pound it out to about 3/8" thick. Thicker will be crumblier, thinner will be crisper.
Cut into whatever size or shape you wish - I vary sizes because it's funny - and place on a cookie sheet. They won't expand much so can be placed fairly close together.
Bake for around 30 minutes. They'll only take a little color on top but when the underside of one is golden brown, you're done.
Take off cookie sheet to cool, on the counter or rack or whatever. Store in a tin if you have one.