Preheat the oven to 190°c (170 fan/ Gas 5) and line a 12 hole muffin tin with muffin cases.
Place the dry ingredients (plain flour, bicarbonate of soda, cocoa powder and caster sugar) in a large mixing bowl.
140 g Caster Sugar, 180 g Plain Flour, 20 g Cocoa Powder, 1 teaspoon Bicarbonate of Soda
Whisk together the wet ingredients (yogurt, melted butter, eggs and vanilla extract) in a small bowl or jug then gently mix into the dry ingredients.
100 ml Natural Yogurt, 2 Eggs, 140 g Butter, 1 teaspoon Vanilla Extract
Fold in the mashed banana and chocolate chips.
200 g Banana, 100 g White Chocolate Chips
Spoon the muffin batter into 12 muffin cases and bake for 18 minutes.