Step 1

Preheat the oven to 350°F (180°C), or 160°C for a fan oven, and line a 12-count muffin pan with paper liners.

Step 2

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

Step 3

In a large bowl, cream together the sugar, butter and orange zest until smooth. Beat in the eggs and vanilla extract.

Step 4

Add the flour mixture and mix until just combined. Add the sour cream and orange juice and gently stir to combine.

Step 5

Divide the batter evenly between the prepared muffin cups. Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted in the center comes out clean.

Step 6

Allow to cool 5 minutes before transferring to a wire rack to cool completely.

Step 7

In a large bowl add half the powdered sugar, butter and orange zest and mix until smooth. Add the remaining powdered sugar and mix well.

Step 8

Add the orange juice and vanilla and mix to combine. Add the heavy cream as needed and mix to achieve desired consistency.

Step 9

Pipe or spread over the cooled cupcakes.