In a large skillet, add 2 tablespoons of olive oil and ½ tablespoon of butter over medium-high heat. Wait until the mixture shimmers, about 1-2 minutes.

Add the sliced zucchini in a single layer to the skillet. Sprinkle with salt and pepper, then sauté for 3-4 minutes, flipping once. Remove the zucchini and set aside.

Add the remaining ½ tablespoon of butter and diced onion to the skillet. Sauté for about 2 minutes until softened.

Add the cleaned button mushrooms to the skillet. Cook undisturbed for 2-3 minutes, then stir and cook for an additional 3-4 minutes.

Stir in 2 minced garlic cloves and fresh herbs. Cook for about 20 seconds, watching not to burn the garlic.

Return the sautéed zucchini to the pan. Pour in ½ cup of vegetable broth and let simmer for 2 minutes.

Adjust seasoning with additional salt and pepper if needed. Serve warm, garnished with fresh parsley and grated Parmesan, if desired.