Preheat the oven to 190°c (170° fan/ 375F/ Gas 5) and line a 12 hole muffin tin with paper cases.
Mix together the caster sugar, plain flour, cocoa powder and bicarbonate of soda in a large bowl.
140 g Caster Sugar, 180 g Plain Flour, 20 g Cocoa Powder, 1 teaspoon Bicarbonate of Soda
Whisk the yogurt, eggs and melted butter together in a bowl, until combined.
100 ml Natural Yogurt, 2 Eggs, 140 g Butter
Gently mix the wet ingredients into the dry ingredients, being careful not to over mix.
Fold in the grated courgette and chocolate chips.
250 g Courgette, 100 g Milk Chocolate Chips
Spoon the mixture into 12 muffin cases.
Bake for 18 minutes. Cool on a wire rack once cool enough to handle.