Into the bowl of a food processor, add flour, powdered sugar and vegan butter. Pulse until the mixture resembles a coarse meal. Then, add the non-dairy milk and vanilla and pulse until the dough just comes together. It should stick to itself when pressed. Remove the dough from the food processor, shape into a disc, and wrap it tightly with plastic wrap. Place in the refrigerator to chill for at least 1 hour, or up to 3 days.
1 ½ Cups Flour, 6 tablespoon Powdered Sugar, 8 tablespoon Vegan Butter, cold, cut into ¼ inch cubes, 3 tablespoon Non-Dairy Milk, ½ teaspoon Vanilla Extract