Step 1: Heat the extra virgin olive oil in a large Dutch oven or heavy-bottomed pot over medium heat. Add the chopped onion and cook for 4 to 5 minutes until translucent and soft.
Step 2: Stir in the minced garlic and cook for 1 minute until fragrant, taking care not to let the garlic burn.
Step 3: Add the sliced mushrooms to the pot. Increase the heat to medium-high and let them cook without stirring for 2 to 3 minutes to get a good sear. Stir occasionally and continue cooking for another 5 to 7 minutes until the mushrooms are deeply browned and their liquid has completely evaporated.
Step 4: Sprinkle the dried thyme, dried oregano, salt, and black pepper over the browned mushrooms. Stir well to coat the mushrooms and toast the herbs for about 1 minute.
Step 5: Pour in the vegetable broth, using a wooden spoon to scrape up any flavorful brown bits stuck to the bottom of the pot. Bring the liquid to a boil, then reduce the heat to low, cover with a lid, and let it simmer for 10 to 12 minutes.
Step 6 (Optional): Use an immersion blender directly in the pot to blend roughly one-third of the soup. This creates a thicker, creamier broth while keeping plenty of whole mushroom pieces intact for texture.
Step 7: Turn the heat to low. Stir in the heavy cream and grated parmesan cheese. Simmer uncovered for 3 to 5 minutes until the cheese is completely melted and the soup is silky and rich. Taste and adjust seasonings with extra salt and pepper if needed, then remove from heat and serve warm.