Combine the first 6 (dry) ingredients in a mixing bowl, plus the optional flaxseeds. Stir together well.
Make a well in the center and pour in the yogurt and nondairy milk. Stir with a whisk until the batter is just smooth; it should have an easy-to-pour consistency, but not too thin. Don't overbeat.
Place the blueberries in a small bowl and sprinkle with flour until they are lightly and evenly coated (this will help prevent the pancakes form turning completely blue). Gently stir them into the batter.
Heat a nonstick griddle or a large, nonstick skillet that has been lightly coated with vegan buttery spread. Ladle on the batter in amounts enough to form 3- to 4-inch pancakes. Cook on both sides until golden brown. Serve hot with maple syrup or preserves.