Heat a large skillet over medium-high heat. Add olive oil and butter, stirring until the butter melts and bubbles.

Add the sliced zucchini to the skillet and sauté for 3-4 minutes until tender and lightly golden. Remove and set aside.

Melt the remaining butter, add diced onion, and sauté for 2 minutes until translucent.

Stir in button mushrooms and cook for 5-7 minutes until browned and tender.

Add minced garlic and fresh herbs. Cook for an additional 20 seconds until garlic is fragrant.

Return the cooked zucchini to the skillet and mix well, heating through for 1 minute.

Pour in vegetable broth and simmer for 2 minutes to combine flavors.

Adjust seasoning with salt and pepper, then garnish with parsley and Parmesan before serving.