Preheat oven to 350F and grease or line a baking pan with baking paper.
Place the portobello mushrooms bottom side up and spread the garlic cream cheese on top. Next, spread tomato paste on top and add the shredded cheese. (If you’re making the vegan version, top with nutritional yeast at this stage).
Next, place the tomato slices on top of the portobello mushrooms and season with salt, pepper and oregano. Top with crumbled gorgonzola cheese (vegan or vegetarian).
Bake the portobello mushrooms in the middle of the oven for 20 minutes or until the mushrooms are cooked through and the cheese have melted and started to turn golden brown.
While the portobello pizza steaks are roasting, lightly grill your burger buns. Once the burger buns are ready, spread vegan mayonnaise and pesto on each bun. Add your salad toppings of choice and place the portobello pizzas in the middle of the burgers. Assemble your burger and enjoy.