Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper.
In a mixing bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and cinnamon until well combined.
In another bowl, combine the milk, melted butter, and vanilla extract. Mix until fully combined.
Gradually pour the wet ingredients into the dry ingredients, stirring until just combined. Be careful not to overmix.
Gently fold in the fresh blueberries until evenly distributed in the batter.
Using a spoon or ice cream scoop, drop the batter onto the prepared baking sheet, forming small mounds. Leave some space between each mound.
Bake in the preheated oven for 15-20 minutes, or until the fritter bites are golden brown and a toothpick inserted comes out clean.
While the fritters are baking, prepare the glaze if desired. In a small bowl, whisk together the powdered sugar, milk, and vanilla extract until smooth.
Once baked, remove the fritter bites from the oven and let them cool for a few minutes before drizzling with glaze or sprinkling with powdered sugar.
Serve warm and enjoy!