Preheat your oven to 375°F (190°C). Grease a 6-cup muffin tin with cooking spray.
In a blender, combine the egg, milk, flour, vegetable oil, salt, and cheese.
Blend until smooth, about 1 minute.
In the greased muffin tin, pour in the batter until each cup is three-quarters of the way full. You may have a bit left over to make a second round of baking.
Place the muffin tin in the oven, and bake for 15–20 minutes, until golden brown and puffy.
Enjoy immediately!