1. Preheat the oven to 200 degrees. Brush the muffin box or put it in the muffin box.

2. Mix flour, sugar, salt and baking powder together. Then mix the oil, eggs and milk into the flour mixture. Then add blueberries. Pour the mixture into the muffin box, flush with the top. Then sprinkle some other ingredients on it to make it crisp.

3. Crispy top: Mix 100g sugar, 50g flour, 50g butter and 1.5 teaspoon cinnamon with a fork, and then sprinkle on the muffin.

4. Bake in the preheated oven for 20-25 minutes.