Preheat oven to 190C. Grease the cups of a muffin pan or line with paper muffin liners.
Sift flour, polenta, brown sugar, salt and baking powder together into a large bowl. Mix in the blueberries. In a small bowl, combine the milk, butter and egg. Stir the wet ingredients into the flour mixture just until moistened. Spoon batter into prepared muffin cups.
Bake in preheated oven for 20 minutes. Let muffins sit for 10 minutes before removing from the pan.