• Preheat oven to 220°C / 425°F and grease or line a muffin pan with 12 paper muffin cups.

Streusel

• In a small bowl combine melted butter, white sugar and all-purpose flour.
• Use a fork to combine this flour mixture into a coarse crumb, then set it aside.

Muffins

• In a seperate bowl, combine the flour, cinnamon, baking soda, baking powder, and salt and whisk together. Set aside.
• In a large bowl, add the oil, eggs, white and brown sugar, vanilla, and yoghurt. Whisk it all together.
• Add the flour mixture, chopped feijoas, and candied ginger. Fold together to combine into a batter.
• Divide the batter evenly over the muffin cases and top with the streusel topping.
• Bake the muffins at 220°C/425°F for 5 minutes, then turn the oven down to 180°C/350°F and continue baking for another 15-18 minutes until the tops of the muffins spring back when lightly pressed.
• Remove them from the oven and let the muffins cool in the pan for 10 minutes before removing the warm muffins and placing them on a wire rack to cool to room temperature.
• The feijoa muffins should be stored at room temperature and gently covered with a clean kitchen towel. Storing them in an airtight container softens the streusel