For the Espresso Shortbread
- 9 tablespoons cold butter
- 1/4 cup caster sugar, plus extra for dusting
- 1 double shot espresso, cooled
- 1 teaspoon coffee extract
- 11/2 cups all-purpose flour
For the Chai Buttercream
- 1/2 cup softened butter
- 13/4 cups powdered sugar
- 1 teaspoon vanilla bean paste
- 5 heaping teaspoons chai powder, mixed with a splash of water to make a paste
Make the espresso shortbread: Preheat the oven to 375ºF. Beat the butter and sugar together until smooth. Add the espresso and coffee extract; mix well. Add the flour and mix until just combined, making sure not to overwork the dough.
Roll the dough out on a lightly floured surface, until 1/4-inch thick. Use a 2-inch round cookie cutter to cut out cookies, then transfer to a lined baking sheet. Re-roll the scraps and repeat until you have as many cookies as possible.
Transfer the baking sheets to the fridge to chill for 20 minutes.
Dust each shortbread with caster sugar just before putting in the oven. Bake for 10-15 minutes, until light golden-brown. Remove from the oven and let cool on a wire rack for at least 1 hour.
Make the chai buttercream: Beat the butter until very pale, light and fluffy. Gradually add the powdered sugar, 1 tablespoon at a time, until it is all incorporated. Add the vanilla bean paste and chai paste. Beat for 30 more seconds until combined. Adjust with more vanilla or chai if desired.
Fill a piping bag with the buttercream. Pipe onto half the cooled cookies, then close each sandwich with another cookie. Refrigerate for 1-2 hours to help the buttercream firm up.