Cook angel hair in a large pot of salted boiling water until al dente. Drain and toss with 2 tbsp butter. Set aside.

In a large sauté pan, heat the remaining 2 tbsp butter and 4 tbsp olive oil over medium heat. Add garlic and onion, cooking until fragrant and lightly golden around the edges.

Stir in mushrooms and sauté until tender.

Add shrimp (if using), cherry tomatoes, and asparagus. Cook for 4–6 minutes, until shrimp is opaque, asparagus is crisp-tender, and tomatoes are softened.

Season with salt, black pepper, and chili flakes if using. Stir in cooked pasta and toss until fully combined.

Plate and top with parmesan cheese if desired. Serve hot.