In the bowl of a stand mixer fitted with the paddle attachment, beat butter until smooth. Add the sugar, and continue to beat until smooth. Add the egg and vanilla pasta, and mix until incorporated, scraping down the sides as needed. Add the flour, sea salt, and five-spice powder, mixing just until combined. Give the dough one last mix with a spatula to smooth out any lumps and make sure no streaks of flour are still visible. Don't have a stand mixer? You can make these by hand or with a hand mixer as well.

Turn the dough out onto a piece of parchment, and roll into a log 1 1/4 - 1 1/2-inch thick. Wrap the parchment around the dough, and chill for at least 1 hour in the fridge. You can make the candied clementines while you wait (recipe below).

Preheat an oven to 325°F, and place a rack in the middle of the oven. Line a rimmed baking sheet with parchment, and set aside.

Take the cookie dough from the fridge, unwrap, and slice into 1/4-inch rounds. Place rounds 2-inches apart on the prepared baking sheet (I fit 13 on 1 baking sheet), then top each round with a slice of candied clementine. The cookies will spread a bit as they bake, so don't worry if the slice completely covers the cookie. Very large clementine slices can cut in half, and halves placed on 2 cookies.