Heat a large skillet over medium-high heat and add olive oil and butter. Allow butter to melt.

Add sliced zucchini, season with salt and pepper, and cook for 3-4 minutes until tender. Remove and set aside.

Wipe skillet if needed, add remaining butter, and sauté diced onion for about 2 minutes until softened.

Add sliced mushrooms and cook for 5-7 minutes, stirring occasionally, until browned and moisture released.

Stir in minced garlic and mixed herbs, cooking for about 20 seconds until fragrant.

Return sautéed zucchini to the skillet, add vegetable broth, toss gently, and simmer for 2 minutes.

Adjust seasoning to taste, then sprinkle fresh parsley and grated Parmesan on top before serving.