Beat the cold vegan butter and powdered sugar in a large bowl with an electric mixer for 2 minutes until light and fluffy. Add the flour and mix on low just until a shaggy dough forms, about 1 minute.

Press the dough evenly into a parchment-lined 8-inch round cake pan. Smooth the top, score into 8 wedges, and prick each wedge a few times with a fork. Chill the pan for at least 30 minutes.

Preheat the oven to 325°F (160°C). Bake the chilled shortbread for 25 to 30 minutes, until the edges are lightly golden and the center looks dry and set.

Let the shortbread cool in the pan for 10 minutes, then lift it out with the parchment. Cut along the score lines while still warm and let the wedges cool completely on a rack.