Preheat oven to 425 degrees.
In a medium sized mixing bowl, combine the almond milk and apple cider vinegar. Let sit while you start the rest so it thickens a bit.
In a large mixing bowl, combine the flour, baking powder, and salt. Whisk together just to combine. Set aside.
Add the vanilla, maple syrup and oil to the almond milk mixture, and stir.
Slowly add the wet ingredients to the dry ingredients, whisking together until fully combined.
Stir in the lemon zest if using. Pour into an 11x16in. sheet pan that is lined with parchment paper and sprayed with non stick spray. Smooth out the batter.
Bake at 425 degrees for about 5 minutes, then sprinkle the berries on top. Rotate and bake another 10-12 minutes, or until fully baked and tooth pick comes out clean. Then if you want to brown the top, you can broil at this point for 3-4 minutes or so until brown. Serve with maple syrup or powdered sugar or both!