Method
Preheat oven to 400F/200C. Grease muffin cups with a little butter or margarine. Put orange quarters in food processor (or blender) along with orange juice and process or blend until pureed. Add eggs and butter to food processor and combine; pour into large bowl. Combine dry ingredients together in a separate bowl, and then add all at once to orange mixture. Stir to combine. Fill muffin cups about ¾ full. Bake in preheated oven for 20 mins; remove from oven and let stand in tin for 5 mins before removing muffins. Serve warm at tea time or use in desserts.