Preheat oven to 350°F and grease a muffin tin with non-stick spray. Set aside.
In a medium mixing bowl, whisk together flour, sugar, cornstarch, baking powder, salt, and cinnamon.
In a separate mixing bowl (or liquid measuring cup) mix together the Greek yogurt, oil, egg, and vanilla.
Add the liquid mixture to the dry and mix with a wooden spoon or rubber spatula. When halfway mixed together, toss in the blueberries and fold together until everything is wet and berries are evenly dispersed.
Fill 9 muffin tin wells with batter (about 1/4 cup each). Sprinkle the sugar on top and then bake 18-22 minutes or until toothpick comes out clean.
Remove muffins from tin by running a knife around the edges. Enjoy warm. Once cooled, store in an airtight container.