In a clean, dry 750ml jar, carefully layer up the ingredients in order, starting with the flour. Tuck the vanilla pod inside or tie it around the lid with a gift tag, after sealing the jar.
Write the following on the gift tag: To bake cookies, preheat oven to 180ºC/gas 4. Open the jar and carefully spoon the sugar into a mixing bowl with 115g softened butter. Split the vanilla pod, scrape out the seeds, add them to the bowl, then beat everything with an electric mixer until pale and fluffy. Mix in 1 large free-range egg. Empty in the rest of jar; combine until smooth. Refrigerate the dough for half an hour, then transfer tablespoons of it to a lined baking sheet. Flatten slightly, leaving room for them to spread.
Bake for 10 to 12 minutes, until golden at the edges but soft in the middle. Leave on the baking sheet for 5 minutes before transferring to a rack to cool.