Preheat the oven to 425°F. Line 12-count muffin tins with paper liners, or spray them with baking spray, set aside.
In a medium bowl stir together the dry ingredients – flour, baking powder, and salt; set aside.
In a large bowl, whisk together the oil and brown sugar until combined. Add the eggs and whisk until smooth. Spoon in the sour cream and whisk until smooth. Mix in the orange zest, orange juice, milk, and vanilla, and whisk until smooth.
Add the flour mixture to the wet ingredients and stir it until just combined with no dry patches. Add the cranberries and white chocolate chips and fold them in.
Divide the muffin batter among the prepared muffin cups. Sprinkle the coarse sugar on top of the muffins if using.
Bake at 425°F for 5 minutes. Reduce the heat to 350°F and bake for an additional 16-18 minutes until golden brown and a toothpick inserted into the center of a muffin comes out mostly clean.
Let the muffins cool in the tin for 5 minutes, then carefully take them out and let them cool completely on a wire rack.
While the muffins are cooling, make the glaze. Mix together the cream cheese and white chocolate in a medium-sized bowl.
Slowly add in the powdered sugar until fully combined and smooth; the mixture will be thick. Add the milk and stir until smooth; if you find it is too thick to drizzle, add a little more milk.
Drizzle the glaze on top of the muffins and serve warm, or allow them to cool completely to set the glaze.