Bring a large pot of water to a boil. Add salt and the spaghetti. Cook according to package directions less 2 minutes. (the pasta will finish cooking in the sauce). A minute before the pasta is done, add the asparagus and peas. Reserve 1/2 cup of the pasta water and then drain.
In a large skillet, melt one tablespoon of butter and add the black pepper. Sauté for about 1 minute or until fragrant. Add 1/4 cup of the pasta water and the remaining one tablespoon of butter. Simmer for about 30 seconds, stirring until the butter is melted.
Add the cooked spaghetti, peas, asparagus, and all three cheeses. Stirring until the cheeses are melted. Add more pasta water if mixture seems too dry. Taste for seasoning and that the spaghetti is tender.
To serve, portion into individual bowls topping with some flaked smoked salmon, a drizzle of extra virgin olive oil, extra cheese and more freshly ground black pepper to taste.