Crosshatch the Sourdough Boule: Preheat oven to 375°F (190°C). Line a large rimmed baking sheet with parchment paper or heavy-duty aluminum foil. Using a sharp serrated bread knife, cut 1-inch parallel slices across the sourdough loaf, slicing down to within 1/2-inch of the bottom crust (do not cut all the way through the base). Turn the loaf 90 degrees and repeat crosswise cuts to create a grid of 1-inch bread diamonds connected at the bottom.

Whisk Rosemary Garlic Butter: In a small bowl, whisk together the melted unsalted butter, minced garlic, chopped rosemary, honey, sea salt, and black pepper until completely blended and fragrant.

Brush Interior Cuts: Using a pastry brush, gently open the bread crevices and brush about half of the garlic rosemary butter deep into all cuts and corners of the bread.

Stuff with Brie, Cranberries & Pecans: Tuck thin slices of Brie cheese into each crosshatched crevice, pressing them down so they nestle deep inside. Spoon the spiced whole berry cranberry sauce generously between the bread diamonds, followed by scattering the toasted chopped pecans into the cuts.

Brush Crust & Bake in Foil: Brush the remaining rosemary garlic butter over the entire top and sides of the loaf. Wrap the loaf loosely in aluminum foil (tenting slightly at the top so melted cheese does not stick to foil) and bake at 375°F (190°C) for 15 minutes. Unwrap the foil, folding it down around the sides to expose the top crust, and bake for an additional 6 to 8 minutes until the cheese is bubbling molten, and the crust points are deeply golden and crunchy.

Garnish and Serve Hot: Transfer carefully to a rustic wooden cutting board or platter. Sprinkle top generously with flaky Maldon sea salt, arrange fresh rosemary sprigs and raw red cranberries around the base, and serve immediately while the cheese is gloriously stretchy and warm!