Preheat the oven to 200 degrees C (fan forced 180). Line a muffin tin with patty cups, or grease with a little oil.
Mix together the dry ingredients in a large bowl. In a separate bowl, mix together the wet ingredients. Pour the wet ingredients into the dry ingredients all at once, and then gently fold together using a rubber spatula. Do not overmix; scrape up from the bottom of the bowl to gently fold together until the mixture is just moistened.
Spoon the muffin mixture into the patty cups, filling the cups 3/4 full. Bake in the preheated oven for 20 minutes, or until a skewer inserted in the centre of a muffin comes out clean. Remove from tin and cool on a wire rack.
To make the orange glaze, mix together all the ingredients, adding more orange juice or icing sugar to adjust the consistency if necessary. Drizzle the glaze over the cooled muffins.