1. Preheat your oven 200°C and line your muffin tin with muffin cases.
2. Combine your wet ingredients (oil, milk, egg) in one bowl and mix well.
3. Add your dry ingredients (Durrow Mills Bakers Mix, sugar, salt, baking powder) in another bowl combine well.
4. With a wooden spoon or spatula, begin stirring your wet ingredients into your dry ingredients until a few flour streaks remain.
5. Stir in your blueberries until well distributed in the batter.
6. Spoon your muffin batter into the cases filling each to the top.
7. If making a crumb top, mix 65g flour and 65g sugar together well. (If you are using cinnamon add it here too.)
8. Add in the cold, cubed butter and with your fingers or a fork, begin breaking up the butter to form a crumb-like texture.
9. Generously sprinkle your crumble topping over your muffins in the cases.
10. Bake in your preheated oven for 20-25 min or until you can poke the centre with a toothpick and it comes out clean.
