Preheat oven to 190C.
Whisk in flour, cocoa powder, sugar, baking powder, baking soda, salt in a large mixing bowl.
In a measuring cup, mix oil, egg, buttermilk, and vanilla until well combined.
Pour in wet ingredients to dry ingredients.
Use a spatula to mix it 4-5 times.
Add the peanutbutter chips and chocolate chips, and fold them in.
The batter should be just combined and a little lumpy.
So not over mix or you will get tough muffins!
Sprinkle the top with the reserved chips.
Bake for 20 mins or until skewer comes out clean.