Preheat oven to 180C/160C fan/Gas 4. Line a 12-hole muffin tin with paper cases.
Sift flour, baking powder, cinnamon, salt into bowl. Stir in muscovado sugar.
Whisk milk, eggs, and melted butter in a jug.
Pour wet into dry, fold by hand. Stop when flour disappears. Lumpy is fine.
Fold in blueberries gently.
Fill cases two-thirds full. Tap tray on worktop at both ends.
Bake 25 minutes until risen, golden, skewer clean.
Cool in tin 5 minutes, then transfer to wire rack.
