- Preheat the oven to 325°F and line two baking trays with parchment paper.
- Beat the butter and icing sugar until light and fluffy, about three minutes. Beat in the vanilla bean paste (or extract). It’s an important step to beat the butter and sugar well together when making shortbread; this ensures the shortbread will hold together and when you take a bite it will ‘snap’ and then melt away.
- In a separate bowl, sift the flour, cornstarch and salt and add to the butter, mixing until blended and soft. Spoon the dough into a piping bag fitted with a large star tip (or into a cookie press). Pipe cookies about 1 ½ inches across onto the prepared baking trays and leaving an inch between each cookie. If you want a flatter cookie that spreads, bake right away. For a cookie that sits up and holds its shape, chill the piped unbaked cookies for 15 minutes before baking. Bake for 20 to 25 minutes, until the cookies just begin to brown lightly on the bottom. Cool the cookies on the trays before storing in an airtight container.
The cookies will keep up to a week.