Preheat the oven to 200C/180C Fan/Gas 6. Line a 6 hole muffin tin.
In a large bowl, combine the dry ingredients (flour, baking powder, orange zest sugar and a pinch of salt).
Make a well and add in the liquid ingredients (melted butter, milk, oil and orange juice).
Stir together very gently with a wooden spoon, until only just combined. Scoop 2-3 tbsp batter into each muffin liner, filling to about 2/3rds full. Bake 15-18 mins.
Make the drizzle: either brush over a little marmalade, or make the drizzle by combining the orange juice and sugar. Brush over the warm muffins.
Once cool, make the glaze by combining icing sugar and orange juice. Dollop a little onto each muffin, add more orange zest and serve!