Preheat the oven to 160°C.

Mix the flour and sugar together in a mixing bowl. Rub in the butter with your thumb and forefinger.

Then add the thyme, lemon zest and vanilla.

Push the dough in a 8 by 8 pan lined with parchment.

Cut into squares or rectangles.

Alternatively, you can roll the dough into a circle and place it onto a baking sheet lined with parchment.

Once done, leave to cool, then put away in an airtight container.