Gather ingredients and prep: Assemble ground beef (2 pounds), ½ cup crumbled Gorgonzola cheese, optional mozzarella, seasonings, and burger buns. Preheat your grill or skillet to medium-high heat.

Form patties: Divide ground beef into 8 equal portions. Flatten 4 portions into thin patties. Evenly distribute about 2 tablespoons of Gorgonzola (and optional mozzarella) on each. Top with the remaining 4 patties and firmly pinch edges to seal the cheese inside, creating stuffed burgers.

Chill patties: Refrigerate the sealed patties for 20 minutes to help them firm up and maintain shape during cooking.

Cook mushrooms: In a skillet, melt butter and sauté minced shallot, garlic, and a mix of porcini (soaked and minced), shiitake, and cremini mushrooms with salt and black pepper. Deglaze with brandy and reserved porcini liquid, cooking until tender. Keep warm.

Make red onion marmalade: Slowly cook thinly sliced red onions in olive oil over low-medium heat until soft and golden (~25 minutes). Add red wine vinegar and brown sugar; cook until syrupy. Stir in heavy cream, season with salt and pepper, and remove from heat.

Grill burgers: Lightly oil the grill or skillet. Cook stuffed patties for 4-6 minutes per side or until internal temperature reaches 160°F (71°C), taking care not to pierce the patties to avoid leaking cheese. Allow resting for 2 minutes.

Toast buns: Brush insides with butter and toast on the grill until golden and crisp.

Assemble: Place each burger on a bun bottom, top with 1 tablespoon red onion marmalade, a generous spoonful of sautéed mushrooms, optional grilled red onions, baby arugula, and a smear of balsamic-fig jam for a sweet contrast. Cover with the top bun and serve immediately.