Add the muffin mix to a medium-sized bowl, then add the egg, oil and milk. Mix well together then fold through the cinnamon, crushed cinnamon grahams and blueberries. Fill the muffin cases evenly with the mixture.
In a small bowl mix together the topping ingredients, rubbing everything together with your fingers. Sprinkle over the top of the muffins then bake for 15-20 minutes. Remove to cool.