Heat oven to 350°F. Line a 9-inch square pan with parchment and lightly grease.
Beat softened butter with both sugars until light and fluffy, about 2–3 minutes.
Mix in eggs, vanilla, and orange zest until smooth and creamy.
Whisk flour, baking powder, salt, ginger, and cinnamon in a separate bowl.
Stir dry ingredients into the butter mixture just until combined. Do not overmix.
Fold in white chocolate chips and chopped cranberries until evenly distributed.
Spread batter into the pan and smooth the top with an offset spatula.
Bake 20–24 minutes until edges are set and a tester lifts a few moist crumbs.
Cool completely in the pan on a rack before frosting.
Beat cream cheese and butter until smooth. Add powdered sugar, vanilla, and zest; blend. Splash in orange juice if needed for spreadability.
Spread frosting over cooled bars. Scatter chopped cranberries on top and drizzle with melted white chocolate.
Chill 15 minutes for clean cuts. Slice into squares or triangles and serve.