Step 1

ready a 9-inch (20x20cm) square baking pan that has been buttered or sprayed with baking spray.

Step 2

it with parchment paper: take a large piece of parchment paper of about 8 inches (almost as wide as the pan) and cover the bottom and two sides of the pan. The other two sides will remain buttered but not lined with paper. This will help you remove the shortbread after it's baked.

Step 3

a large bowl mix soft butter with the lemon zest and vanilla.

Step 4

the powdered sugar and incorporate well so there are no lumps. I recommend sifting the sugar before adding, or sifting it directly over the butter mixture as I do.

Step 5

the flour and salt in 2 parts, mixing with the spatula until it is smooth, well combined and no dry spots remain.

Step 6

the dough to the prepared pan, scattering small amounts on the bottom.

Step 7

your hand, lightly pat the dough until it covers the whole surface. Make sure the edges are covered. Make it as even as possible, but relax because it will not be very smooth.

Step 8

the whole pan, covered in plastic wrap, for 1 hour or up to 24 hours.

Step 9

oven to 325°F/160*C.

Step 10

the granulated sugar over the top before baking.

Step 11

the shortbread for 40-45 minutes, until the top is dry, it has puffed a little and is beginning to color. You can leave a couple more minutes if you want a more golden shortbread. Just don’t let it dry out.

Step 12

cool 10 minutes on a wire rack and carefully cut into sticks or squares o triangles with a smooth bladed knife.

Step 13

cool on the cooling rack completely, lift the whole square of the pan with the aid of the parchment paper, and carefully break each piece.

Step 14

in airtight cookie jars or tins.