Cube the Portobello mushrooms and remove the gills.

Sauté the mushrooms for 4-5 minutes over medium heat with a little olive oil if desired, then set aside.

Mince the broccoli and red onion, ensuring they are finely chopped.

In a large bowl, mash 1 cup of the black beans with a fork or potato masher until mostly smooth but with some texture.

Leave the other cup of black beans whole for added chunkiness.

To the mashed beans, add the sautéed mushrooms, whole black beans, minced broccoli, red onion, and garlic.

Stir until well mixed.

Add the beaten eggs, Panko breadcrumbs, Montreal steak seasoning, Worcestershire sauce, and grated Parmesan cheese.

Combine thoroughly until all components are evenly blended and the mixture forms a cohesive mass.

Using your hands, form the mixture into burger patties.

You should get about 6-8 medium-sized patties, depending on your preferred size.

Heat a tablespoon or two of olive oil in a large skillet over medium heat.

Once hot, add the veggie patties and cook for 4-5 minutes on each side, or until golden brown and cooked through.

For an extra crispy finish, place the patties in a preheated oven at 375°F (190°C) for an additional 10 minutes after pan-frying.

Serve the chunky Portabella veggie burgers on a bun with your favorite toppings like lettuce, tomato, avocado, or even some extra cheese or sauce.