1. Preheat your oven to 350 degrees.

2. Into the bowl of a food processor, stand mixer, or if you're in for a little workout, a regular bowl, place the butter, vanilla, salt, grapefruit zest and chopped thyme.

3. Add the powdered sugar and pulse (if using a processor), or beat on medium with a paddle (if using a stand mixer), or mix with a wooden spoon until mixture is smooth.

4. Add the all purpose flour and mix just until flour is incorporated.

5. Butter a springform pan or pie tin.

6. Using an offset spatula, spread the dough evenly in the pan.

7. Prick the surface of the dough with a fork. This is called "docking."

8. Refrigerate for an hour (or put it in the freezer for 30 minutes).

9. While your dough is getting cold, squeeze out about 2 TB of grapefruit juice into a bowl. Add 3/4-1 cup of powdered sugar and a pinch of salt. Whisk until smooth. 10. Once the dough is cold, put in the oven for 15-18 minutes until the edges are golden and the center is firm.

10. Once the dough is cold, put in the oven for 15-18 minutes until the edges are golden and the center is firm.

11. Remove the collar from the pan. Immediately cut the shortbread into 8 or 16 wedges.

12. Transfer wedges to a cooling rack set over a plate.

13. Drizzle the glaze evenly over the shortbread, and gently spread to the edges with an offset spatula. Once cool you can serve it!