In a medium bowl, combine the flour, granulated sugar, baking powder, salt, and ground cinnamon. Mix well and set aside.
In another bowl, whisk together the milk, egg, and vanilla extract until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Gently fold in the Cheerios until they are evenly coated with the batter.
In a large skillet or deep fryer, heat about 2 inches of vegetable oil over medium heat until it reaches 350°F.
Using a small cookie scoop or spoon, drop rounded tablespoons of the batter into the hot oil, being careful not to overcrowd the pan. Fry until golden brown, about 2-3 minutes per side.
Remove the fried Cheerios with a slotted spoon and drain on paper towels.
While still warm, dust with powdered sugar before serving.