Grease and chill the muffin tin or fill with paper cups. Preheat the oven to 190°C top/bottom heat. For the dough, cream the butter with the sugar. Stir in the eggs. Mix the coconut flakes, flour, baking powder and orange zest and stir in briefly and quickly together with the yogurt and orange juice.
Pour into prepared pan and bake in preheated oven for about 25 minutes.
Let cool. Boil the orange marmalade with the water, brush the muffins with it and sprinkle with coconut flakes.