Preheat your oven to 350°F. Grease a 9-inch square pan and place one sheet of parchment paper across the pan, with the sides overhanging the edges. Grease the parchment paper and place a second sheet of parchment paper across the pan in the other direction, the sides overhanging the edges. Set the pan aside.

In a small bowl, place the flour, xanthan gum, salt, baking soda and orange zest, and whisk to combine well, breaking up any clumps of zest. Place the white chocolate chips and dried cranberries in a separate small bowl, add about 1 teaspoon of the dry ingredients and toss to coat. Set the chips and cranberries aside. In a large bowl, place the butter and beat with a handheld mixer on medium-high speed until light and fluffy. Add the brown sugar, and then the eggs and vanilla, beating until smooth after each addition. Add the flour mixture and beat until just combined. Add the chips and cranberries with the reserved dry ingredients, and mix until just evenly distributed throughout. The batter should be very thickly pourable.

Pour the batter into the prepared baking pan and spread into an even layer. Place in the center of the preheated oven and bake until firm to the touch and a toothpick inserted in the center comes out clean or with a few moist crumbs attached (about 28 minutes). Remove from the oven and allow to cool completely in the pan.

Place the cream cheese in a large bowl and beat with a handheld mixer at medium speed until light and fluffy. Add the confectioners’ sugar and salt, and beat on low speed until the sugar is absorbed into the cream cheese. It will clump. Increase the mixer speed to medium-high and beat until thick and creamy. Place 2 ounces of the white chocolate in a small, microwave-safe bowl and melt in 15 second bursts, stirring in between, until smooth. Drizzle the melted white chocolate into the cream cheese frosting and beat to combine well. Spread the frosting into an even layer on top of the cooled bars, still in the pan. Sprinkle the dried cranberries evenly over the top of the frosting and press down gently to help them adhere. Melt the remaining 2 ounces white chocolate and drizzle on top of the cranberries. Place in the refrigerator until set.

Remove from the refrigerator and remove the bars from the pan by lifting up on the overhung parchment paper. Using a sharp knife, slice the bars into 6 equal rectangles (slice the square in half, then each half into 3 equal rectangles), then slice each rectangle in half diagonally to create 12 triangles.