In a large skillet, warm the olive oil and ½ tablespoon of butter over medium-high heat. Wait until the butter is melted and the surface shimmers.
Add the sliced zucchini in a single layer. Sprinkle with salt and pepper. Let them sauté for 3 to 4 minutes, flipping once for even browning. Remove from the skillet and set aside.
Drop in the remaining butter and let it melt. Add the diced onion and cook for 2 minutes, stirring often, until it starts to soften and smell sweet.
Add the cleaned, dried mushrooms. Let them cook undisturbed for 2 to 3 minutes to get a good sear, then stir occasionally and cook another 3 to 4 minutes until they’re browned and tender.
Stir in the minced garlic and herbs. Cook for about 20 seconds—just until fragrant. Be careful not to burn the garlic.
Return the zucchini to the pan and toss everything together gently.
Pour in the vegetable broth, scraping up any bits from the bottom of the skillet. Let it all simmer for 2 minutes so the flavors meld.
Taste and adjust salt and pepper. Sprinkle with chopped parsley and a shower of grated Parmesan just before serving.
