Preheat your oven to 350°F. Grease a 13×9-in. baking pan or line it with parchment paper.
In a large bowl, combine the melted butter and brown sugar, whisking until smooth. Incorporate the eggs and vanilla extract into the mixture.
In a separate bowl, mix together the flour, baking powder, salt, and baking soda.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
Gently fold in the white baking chips, chopped walnuts, and dried cranberries.
Evenly spread the batter into the prepared baking pan.
Bake for 22–25 minutes, or until the top is golden brown and a toothpick inserted near the center comes out clean.
Allow to cool completely in the pan on a wire rack before cutting into bars.