Preheat oven to 350ºF and line a 9x9 metal baking pan with parchment paper.
Mix dry ingredients: In a small bowl combine flour, baking soda, salt, cinnamon and ginger. Set aside.
Mix wet ingredients: In a large glass bowl, melt butter on half power in 30 second increments, until fully melted. Allow to cool for 5 minutes then add granulated sugar and brown sugar, whisking until smooth. Add the egg, egg white and vanilla extract, whisking until fully combined and mixture is smooth.
Combine: Add in bowl of dry ingredients and orange juice, stirring a few times, then fold in cranberries and white chocolate chips.
Bake: Transfer batter to lined baking pan, making sure to get the batter into all four corners – the batter is pretty thick, you can use slightly damp hands to help push the batter evenly into the pan. Bake bars for 13-18 minutes, OR until edges are slightly risen and center looks glossy. Don't over-bake or your bars will be dry.
Cool: Allow bars to cool in the pan for 45 minutes before transferring to a wire rack to cool completely. Bars must cool completely before frosting.
Frosting: Once bars have cooled, make the frosting by using an electric mixer to whip the softened cream cheese until creamy. Add in the confectioners sugar and vanilla extract, mixing again on low speed until frosting is smooth. Spread frosting on cooled bars, then top with chopped cranberries and orange zest. For the finish, top with melted white chocolate drizzle (optional but gives them the Starbucks look.)
To cut into triangles, use a large sharp knife and cut into 4 squares. Then cut diagonally, corner to corner, so you end up with 8 triangles. Finally, cut each of the triangles diagonally, so you now have 16 triangles.