In a medium bowl, combine flour, sugar, baking powder, cinnamon and salt until well blended.
In a small bowl, whisk together milk, egg, butter and vanilla. Slowly add the wet ingredients to the dry, stirring with a spatula just until combined. Gently fold in the blueberries.
Heat about 3-4 inches of canola oil in a Dutch oven over medium-low heat. Do not heat the oil too quickly or above medium heat or the fritters will burn.
Drop batter by the tablespoonful into the hot oil. I usually put in 5 at a time. Do not leave the pot while the fritters are cooking. Flip occasionally to promote even browning. Cook for approximately 2-3 minutes until fritters are cooked through.
Remove from pot with slotted spoon and let drain on a paper towel lined plate. Dust with powdered sugar. Serve warm.