Preheat the oven to 180℃. Prepare a muffin tin.
Beat oil and butter until creamy with sugars.
Add eggs, milk with vanilla sirup and beat well until the consistency is thick and bigger.
Add flour, and baking powder and mix with a rubber spatula until there are no lumps with a rubber spatula. In the end, add blueberries and fold them in.
In another bowl mix all the ingredients for streusel.
I recommend using paper muffin cups. Fill them with the batter and add a few blueberries on top with streusel topping. Bake for 20-25 minutes or until the toothpick comes out clean.