In a large mixing bowl, combine the melted butter, brown sugar, granulated sugar, vanilla extract, salt, and orange zest. Mix until fully blended.
Whisk in the eggs one at a time, ensuring the mixture is smooth and cohesive before adding the next egg.
Sift in the flour and baking soda, stirring gently just until combined. Be careful not to overmix.
Fold in the white chocolate chunks, cranberries, and walnuts (if using) until evenly distributed.
Cover and chill the dough for 1 to 2 hours (or overnight). This step is key for achieving thick, chewy cookies.
Preheat your oven to 375°F (190°C) and line baking sheets with parchment paper.
Scoop the dough into 1.5-ounce balls (approximately 2 tablespoons each) and arrange them 3 inches apart on the prepared baking sheets.
Bake in batches for 8 to 10 minutes, or until the edges are lightly golden and the centers are just set. Rotate pans halfway through for even baking.
Allow the cookies to cool on the baking sheet for 1 minute, then transfer them to a wire rack to cool completely.