Preheat the oven to 350F & then grease & parchment line your cake pan(s)
Combine the vegetable oil with the melted vegan butter add the vanilla extract and set aside
Combine the plant milk with the vinegar & let stand for 5 minutes to thicken. *Soy milk is the only plant milk that will thicken, but you can use any plant milk you prefer
Sift all the dry ingredients together in a large mixing bowl, including the sugar.
Pour the wet ingredients into the dry in the bowl & whisk smooth, this will be the plant milk mixture & the butter/oil mixture
Pour the batter into the greased & parchment lined pans & bake immediately in the preheated 350°F oven for 15 minutes, then turn the open temperature down to 325°F to bake the rest of the way, approximately 10-15 minutes more depending on the size pans you are using. When you gently press the centers they should be springy to the touch. Or do the toothpick test for moist crumbs.
Cool in the pan(s) until you can safely touch without burning yourself then turn the cake(s) out onto a cooling rack to cool the rest of the way
Prepare the blackberry compote by combining the blackberries, sugar & water together in a medium sauce pot & cook stirring occasionally over medium heat Bring to a boil then reduce the heat to a simmer & cook until the berries start to break down slightly
Add 1 tsp of water to the 1 tsp of cornstarch in a small bowl & then turn up the heat & return the compote to a boil & then add the cornstarch slurry stirring well to incorporate boil for 30 seconds then remove from heat to cool
Once the compote is cooled to cold & the cake layers are also cooled completely prepare your favorite vegan whipped cream & whip to medium stiff peaks *add amount of confectioners sugar while whipping as desired or none at all for a lower sugar version
Notes
Storage Blackberry Vanilla Cream Cake must be kept refrigerated at all times & will stay fresh wrapped (covered) loosely for up to 5 days