Preheat oven to 200C.
Line your muffin tray.
In a large mixing bowl, sift together baking soda, baking powder, flour, and salt.
Whisk in brown and castor sugar.
Then add your wet ingredients, eggs, buttermilk, oil, and vanilla extract.
Mix until almost combined and still lumpy.
Fold in 1 cup of chocolate chips, make sure not to over-mix batter.
It should still appear lumpy.
Fill liners till almost full, and top with the other 1/2 cup of chocolate chips.
Bake at 200C for 18-22 minutes or until skewer comes out clean. (Mine was about 20 minutes)
Let cool in pan for 5-10 minutes, then transfer to wire rack to cool completely.