Heat oven to 200°C or 390°F.
Mix dry ingredients (flour, baking powder and soda, sugar, and salt) Gently stir in the toppings.
In a separate bowl whisk together wet ingredients (yoghurt, milk, butter, oil, eggs, and vanilla).
Make a well in the dry ingredients and pour the wet ingredients into it. Stir gently. Less stirring is better. No more than max 8 stirs. It is ok if it is lumpy or that some of the flour is not quite mixed in. If you stir too much the muffins will come out hard.
Divide into greased muffin tins. This recipe makes 24 small muffins. Top each muffin with some chocolate chips.
Cook on 390°F for 5 mins. Turn down heat to 350°F and bake for another 12 mins.