Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners.
In a mixing bowl, whisk together the flour, baking powder, baking soda, and salt until well combined.
In another bowl, cream the softened butter and granulated sugar together until the mixture is fluffy.
Add the eggs one at a time, mixing well after each addition. Then, stir in the vanilla extract, fresh orange juice, and the zest of the orange.
Start adding the dry ingredients alternately with the sour cream to the butter mixture. Begin and end with the dry ingredients and mix until just combined.
Gently fold in the chopped cranberries and white chocolate chips.
Divide the batter evenly among the muffin cups, filling them about two-thirds full. Bake for 18–20 minutes, or until a toothpick inserted in the center comes out clean. Let them cool completely.
For the frosting, beat the softened butter and powdered sugar together until smooth and creamy. Stir in the vanilla and fresh orange juice. Finally, add the melted white chocolate and mix until fluffy.
Frost the cooled cupcakes with the creamy frosting. For a fun touch, top with extra cranberries or more white chocolate chips.