Preheat oven to 350 degrees. Combine flour and baking powder in a small bowl. Combine vanilla, milk substitute, and agave nectar or maple syrup in a measuring cup. Add contents of measuring cup to dry ingredients and mix until smooth. The batter will be runny. Pour the batter into a non-stick 8-inch-square pan. Sprinkle the blueberries over the batter. Bake for 45 minutes or until browned.