Step 1: Preheat your oven to 375°F (190°C). Lightly grease a mini muffin tin (or a regular muffin tin, adjusting bake time).
Step 2: In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, cinnamon, and salt. Set aside.
Step 3: In a separate medium bowl, whisk together the granulated sugar, buttermilk, melted butter, egg, and vanilla extract until well combined.
Step 4: Pour the wet ingredients into the dry ingredients. Stir gently with a spoon or spatula until just combined. Do not overmix; a few lumps are okay.
Step 5: Gently fold in the blueberries. If using frozen, add them directly from the freezer.
Step 6: Spoon the batter into the prepared mini muffin tin, filling each cup about two-thirds full.
Step 7: Bake for 15-18 minutes, or until golden brown and a toothpick inserted into the center of a fritter bite comes out clean. (For regular muffin tins, bake 20-25 minutes).
Step 8: While the fritter bites are baking, prepare the glaze: In a small bowl, whisk together the powdered sugar, milk, and vanilla extract until smooth. Add more milk, a tiny bit at a time, if needed, to reach a pourable consistency.
Step 9: Remove the fritter bites from the oven and let them cool in the pan for a few minutes before transferring them to a wire rack. Drizzle generously with the prepared glaze while still slightly warm.