Combine dry ingredients for the topping (flour, sugar, baking powder and salt) in a large mixing bowl.
1 cup (125 g) all purpose flour, ⅓ cup (70 g) granulated sugar, 1 teaspoon baking powder, ⅛ teaspoon salt
Rub the vegan butter into the flour mixture with a fork or a pastry cutter until you have only small pieces of butter remaining.
¼ cup (55 g) vegan butter
Make vegan buttermilk, by stirring together soy milk, lemon juice and vanilla extract in a jug or medium bowl.
⅓ cup (80 ml) soy milk, 1 teaspoon vanilla extract, 1 teaspoon lemon juice
Mix dough. Add the buttermilk mixture to the ingredients in the mixing bowl and gently mix into a rough, sticky dough using a spoon or silicone spatula.
Prepare peaches. Peel if desired, then slice in half, remove pit and cut into slices.
Make peach filling directly in a 8 x 8 inch (20cm) baking dish, by stirring together sliced peaches, granulated sugar (to taste) and cornstarch.
4 cups peaches, 1-4 tablespoons granulated sugar, 1 tablespoon cornstarch
Spread crisp mixture evenly on top of the peaches.
Bake at 350℉ / 180℃ for 30-35 minutes, until the top is light golden brown and the peach mixture is bubbling and looks saucy.
Serve warm and enjoy, with a scoop of vegan vanilla ice cream!