Heat oven to 375°F / 190°C.
Prepare a 12 muffin tin with paper liners and spray with nonstick cooking spray. (I highly recommend using paper liners with blueberry muffins because blueberries that come in contact with the pan have a tendency to caramelize and stick. They are much easier to remove if baked in paper liners.)
In a large mixing bowl, whisk together flour, sugar, baking soda, baking powder, and salt.
In a second, smaller mixing bowl, whisk together yogurt, egg, vanilla, oil, and milk.
Pour wet ingredients over dry ingredients and stir just until no dry spots remain. (To keep the muffins light and tender, do not overmix. If using plain yogurt, the batter will be fairly thin; if using Greek yogurt, the batter may be thicker - both are fine.)
Gently fold in blueberries.
Scoop batter into prepared muffin tin.
Top each muffin with rolled oats or large grain sugar, if using.
Bake until muffins are light golden on top and a tester inserted in the middle comes out clean, 20 to 24 minutes.
Allow muffins to cool in pan for at least 10 minutes and serve.