Preheat the oven to 190°C (170°fan/ Gas 5/ 375°F).
Place the caster sugar, plain flour, cocoa powder and bicarbonate of soda 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 (cooled) melted butter, yogurt and eggs and then pour the mixture onto the dry ingredients. Gently mix with a spoon. Be careful not to overmix.
100 ml Natural Yogurt, 140 g Butter, 2 Eggs
Fold through the chocolate orange pieces and orange zest.
157 g Terry's Chocolate Orange, 1 Orange
Divide the mixture between 12 muffin cases and bake in the oven for 18 minutes (start checking after 16 minutes).
Allow the muffins to cool completely.
For the topping, melt the dark chocolate in the microwave and smear a small amount of the melted chocolate on the back of each chocolate orange minis segment before placing on top of each muffin.
50 g Dark Chocolate, 12 Chocolate Orange Minis segments