
Pre-heat oven to 350° (180° C). Grease muffin tins.
In a small bowl combine sugar, butter and flour until crumbly then stir in chips and set aside.
In a medium bowl whisk together flour, sugar, baking powder and salt. Stir in orange rind. Make a well in the center and add egg, milk, orange juice and oil. Stir just until moistened (10-12 stirs). Transfer into the prepared muffin tins and sprinkle with the topping. Bake for approximately 15-20 minutes. Enjoy!