Preheat oven to 350°F (175°C) and lightly grease a mini donut pan with non-stick spray.

In a large mixing bowl, whisk together the flour, granulated sugar, baking powder, salt, and nutmeg.

In a medium bowl, whisk together the milk, eggs, melted butter, and vanilla extract until combined.

Pour the wet ingredients into the dry ingredients and stir until just combined, being careful not to overmix.

Gently fold the chopped blueberries into the batter.

Transfer the batter into a piping bag and pipe into the prepared donut cavities, filling each about two-thirds full.

Bake for 8 to 10 minutes or until the donuts spring back when lightly touched.

Allow the donuts to cool in the pan for 5 minutes before transferring to a wire cooling rack.

In a small bowl, whisk the powdered sugar, blueberry puree, and additional milk until a smooth, thick glaze forms.

Dip the top of each cooled donut into the blueberry glaze and return to the wire rack until the glaze sets.