Bring a large pot of salted water to the boil and add the spaghetti. Heat a large frying pan over medium heat and add the oil. Add the spring onions and garlic and fry for about a minute until fragrant. Add the asparagus and fry for just a minute until barely tender. Add the peas and mascarpone (or cream cheese) and a little of the pasta water. Mix to a creamy sauce and season well with salt and pepper.
When the spaghetti is al dente, transfer it to the vegetables with a little more of the pasta water. Add the lemon zest and juice and the basil leaves and toss everything together. Drizzle with a little extra olive oil to serve.
