I've tried and tried, finally I found the right formula for a fluffy, light, moist and not-so-sweet muffins.
Ingredients A.
1 3/4 cup self rising flour
1 tsp baking soda
1/4 cup cocoa powder (or less)
Ingredients B.
1 egg (large)
100g butter (melted)
1/2 tsp vanilla
1/2 cup caster sugar
1 cup yogurt (fruit flavor or plain) or replacement, see below
1/2 cup milk
Ingredients C.
A handful of dark chocolate chips
Steps:
Mix A together, sift it twice. Add C.
Mix B together
Pour A to B and lightly mix together
Texture should be lumpy, not smooth
Bake at 190C for 12-15 mins or when it is done. Makes about 6 large muffins.
If you use smaller muffin cups, reduce time to 10-12 mins.
If you don't have yogurt, you can use thick cream + juice from half a lemon.