Cook the pasta in salted water according to package directions. A few minutes before the pasta is done, add the asparagus and finish cooking until the pasta is "al dente". Before draining the pasta, add the frozen peas into the pot. This will defrost the peas and make them soft. (if using fresh peas read the notes below). Reserve 1/2 cup cooking water, then drain.
While the pasta cooks, cook the pancetta. Depending on how much fat the pancetta has, sometimes a little oil is needed. Use a teaspoon of oil to grease the skillet (optional). In a large skillet over medium heat, cook the pancetta until crispy. Remove from the skillet and transfer to a plate lined with paper towels. Drain any excess fat from the skillet.
To make the Lemon Pasta Sauce, in the same skillet, melt the butter over medium heat. Once melted, sprinkle in the flour and whisk constantly for about a minute.
Slowly, pour in the wine or broth and continue to whisk until it begins to thicken. Slowly, pour in the heavy cream and continue to whisk until it begins to thicken.
Stir in the garlic, lemon juice, lemon zest and Parmesan cheese. Season to taste with salt and ground black pepper.
Add the pancetta, the drained pasta, asparagus, and peas into the skillet and toss gently. Add some of the cooking water if a creamier consistency is desired.
Serve immediately topped with additional Parmesan cheese and chopped parsley or basil.