Bring a large pot of salted water to the boil.
Add the asparagus and cook for 3–4 minutes until tender-crisp. During the final minute, add the peas.
Using a slotted spoon, transfer the vegetables to a colander and set aside.
In the same boiling water, cook the wholewheat fusilli according to packet instructions until al dente.
Before draining, reserve 1 cup of pasta water.
Meanwhile, heat the olive oil in a large sauté pan over medium heat.
Add the crushed garlic and cook for 1–2 minutes until lightly golden and fragrant.
Add the asparagus and peas back into the pan. Season with salt and black pepper and toss together for another minute.
In a small bowl, whisk together the egg yolk, grated Parmigiano-Reggiano, ¼ cup reserved pasta water, and black pepper until smooth and glossy.
Return the drained pasta to a baking dish.
Quickly stir through the egg and parmesan mixture, mixing it well until it becomes silky and coats the pasta. Add more reserved pasta water if needed.
Fold through the asparagus and peas.
Finish with extra parmesan, cracked black pepper, lemon zest, or parsley if desired. Oven bake for 15 minutes to melt the cheese (optional).