Preheat your oven to 350°F (175°C). Line an 8x8-inch square metal baking pan with parchment paper, leaving an overhang on the sides for easy lifting. Lightly butter the parchment paper.

In a heatproof bowl set over a saucepan of gently simmering water, melt the chopped bittersweet chocolate and cubed butter together, stirring frequently until smooth and glossy. Remove from heat, whisk in the Dutch cocoa powder and espresso powder until silky, and let cool slightly.

In a separate large mixing bowl, beat the room-temperature eggs, granulated sugar, and brown sugar with an electric hand mixer on medium-high speed for a full 4 to 5 minutes until pale, thick, and ribbon-like. This step is essential for creating the iconic shiny crinkly top crust.

Slowly stream the melted chocolate butter mixture into the whipped eggs, whisking constantly until fully incorporated. Add the vanilla extract and fine sea salt.

Switch to a flexible silicone spatula, add the sifted all-purpose flour, and fold gently just until no dry streaks remain. Do not overmix. Gently fold in 3/4 cup of the dried cranberries and the dark chocolate chunks.

Pour the thick batter into the prepared pan, smoothing the surface with an offset spatula. Scatter the remaining 1/4 cup of cranberries over the surface. Bake at 350°F (175°C) for 26 to 28 minutes, until the top is shiny and cracked, and a toothpick inserted into the center comes out with moist, fudgy crumbs.

Immediately sprinkle flaky Maldon sea salt over the hot surface. Allow the brownies to cool completely in the pan for at least 2 hours (or chill for 1 hour in the refrigerator) for clean, sharp bakery cuts before lifting out and slicing into 16 squares.