Preheat the oven to 325 F.
In a large bowl, beat the butter and sugar for about a minute, until pale and light.
Slowly beat (or stir) in the flour and salt.
Once the dough comes together, knead it a few times, until it’s well-blended and smooth.
You can roll the dough out and cut it into shapes with a cookie cutter or knife, or shape it into two logs to refrigerate, then slice and bake for 10-14 minutes, until pale golden.
For petticoat tail shortbread, divide the dough between two 8 or 9-inch round cake pans, cut each into 12 wedges and press around the edges with the tines of a fork, then bake for about 20 minutes, until pale golden.
To bake in the style of Nancy Carroll’s mother, roll it out to about ⅛-inch thick, transfer to a baking sheet and cut into strips, squares or whatever shapes you like by running a knife or pizza wheel lengthwise and crosswise through the dough.
Poke each piece once or twice with a fork.
Bake for about 20-25 minutes, until pale golden.
Cut along the same lines you scored while the cookie is still warm, and let them cool on the sheet.
