Preheat griddle to 325º. (This is a thick batter and needs to cook at a slightly lower temperature, because they brown up quickly.)

In a large bowl, whisk together the flour and cornstarch until well combine; whisk in baking powder and salt. Set aside.

In a large bowl, beat the egg whites and beat until soft peaks form.

In blender jar add the ricotta, milk, egg yolks, sugar, lemon zest and juice and pulse until smooth. Add to flour mixture and mix just until blended.

Using a rubber spatula, gently fold the beaten egg whites into the pancake batter.

Spray the griddle with nonstick cooking spray. Ladle ⅓ cup batter onto the griddle for each pancake. Add blueberries to each pancake. Cook until bubbles form on top and the pancakes are golden underneath, 1 to 2 minutes. Flip the pancakes and cook for 1 minute more. Repeat with the remaining batter.