Whisk together the flour, cornstarch, sugar, baking powder and salt in a small bowl.
In a medium bowl, whisk together the yogurt, egg, milk, oil and extract. Add in the dry ingredients and whisk until combined.
Preheat your Wonderffle Cast Iron Stuffed Waffle Maker on medium heat, heating up about 2-3 minutes per side and spraying liberally with cooking spray.
Pour just over 1/2 of the batter to cover the griddles. Sprinkle the blueberries on followed by 1 tsp sugar. Then, put the cream cheese on, smoothing out very gently, followed by the remaining sugar.
Gently pour over the remaining batter.
Cook for 5 minutes, flip and cook another 4-6 minutes until golden brown.
Use the tongs to remove the waffle to a plate (If it sticks a little, just use a butter knife to loosen the edges.)