Bring a large pot of salted water to a boil. Add penne pasta and cook for about 8 minutes.
During the last 2–3 minutes of boiling, add the cooked shrimp to heat through. Drain and set aside.
In a large skillet, heat olive oil over medium heat. Add asparagus and red pepper flakes; sauté for 3–4 minutes.
Add chopped garlic to the skillet and cook until the asparagus is tender-crisp and garlic is fragrant, about 4 more minutes.
In a large mixing bowl, combine the drained pasta and shrimp with the sautéed asparagus and garlic.
Stir in Parmesan cheese, season with salt and black pepper to taste, and toss everything until evenly coated.
Serve warm, optionally garnished with fresh parsley or lemon zest.