Prepare the Pan: Preheat the oven to 350°F and line an 8×8-inch baking pan with parchment paper, then lightly grease the pan.
Combine Dry Ingredients: Whisk the all-purpose flour, salt, and cocoa powder together in a medium bowl until evenly combined.
Melt Chocolate Mixture: Place the coarsely chopped dark chocolate and unsalted butter in a large glass bowl. Microwave for 30 seconds, then stir. Continue microwaving in 30-second intervals, stirring after each one, until the chocolate and butter are completely melted and smooth. Add Sugars: Add the granulated sugar and light brown sugar to the melted chocolate mixture. Whisk until the sugars are thoroughly incorporated, then allow the mixture to reach room temperature.
Add Eggs Vanilla: Whisk the 2 eggs into the cooled chocolate mixture until combined. Stir in the vanilla extract. Avoid overbeating at this stage, as excessive mixing can produce cakier brownies.
Fold in Flour: Sprinkle the prepared flour mixture over the chocolate mixture. Using a rubber spatula rather than a whisk, gently fold until the batter is nearly combined and only a small amount of flour mixture remains visible.
Add Cranberries: Fold in the dried cranberries, chocolate-covered cranberries or chocolate chips, and fresh or frozen cranberries until they are distributed throughout the batter.
Bake Brownies: Transfer the batter to the prepared pan and bake at 350°F for about 30 minutes, or until a toothpick inserted into the brownies comes out with moist crumbs attached.
Cool Completely: Allow the brownies to cool completely in the pan before cutting, ensuring they are firm enough to slice cleanly.
Cut Brownies: Using a very sharp knife, cut the cooled brownies into 16 equal squares.
