Preheat oven to 425°F (218°C)

Grease donut pans thoroughly with butter or non-stick spray

Have piping bag or ziplock bag ready for batter (optional)

Whisk together flour, sugar, baking powder, salt, and nutmeg

In separate bowl, whisk buttermilk, eggs, melted butter, and vanilla

Add wet ingredients to dry ingredients, stir until just combined

Gently fold in blueberries, being careful not to crush them

Spoon batter into prepared donut pans, filling 2/3 full

Alternatively, transfer batter to piping bag and pipe into cavities

Smooth tops with moistened finger for even baking

Bake for 8-10 minutes until donuts spring back when touched

Rotate pans halfway through baking for even browning

Cool in pans for 5 minutes before transferring to wire rack

Whisk together powdered sugar, liquid, and vanilla for glaze

For blueberry glaze: simmer 1/2 cup blueberries with 1 tbsp water, strain, use juice

Dip cooled donuts in glaze or brush with pastry brush

Add toppings while glaze is still wet for better adhesion

Allow glaze to set for 15-20 minutes before serving

Best enjoyed day they're made but keep well for 2 days

Refresh in microwave for 10 seconds if stored overnight