Preheat the oven to 180 degrees celsius. Grease a 12 pan muffin tray with butter or spray oil.
To make the crumb topping, in a bowl combine the flour, sugar and cinnamon. Stir to combine. Add the melted butter and stir until tiny balls of dough start to form. This will be a crumb-like texture. Chill in the fridge while you make the muffin batter.
To make the muffin batter, combine the flour, sugar and baking powder in a large bowl. Whisk to combine.
In a small bowl, combine the butter, egg and milk.
Make a well in the centre of the dry ingredients and pour in the wet ingredients. Using a whisk, gently whisk the mixture until just combined. Take care not to overwhisk.
Add the fresh blueberries and fold in with a spatula until just combined.
Divide the mixture among the 12 muffin tins filling them about 1/2 fill.
Remove the crumb topping from the fridge and sprinkle a teaspoon of mixture on top of each muffin batter.
Place the tray in the oven and cook for 20-30 minutes or until a skewer inserted comes out clean.
