One Pot Pasta Primavera

4 cups low-sodium vegetable broth
8 ounces linguine, uncooked
1 small onion, halved and sliced thin
1 pound broccoli crowns, cut into large florets (about 2 cups)
1 1/2 pounds asparagus, ends snapped off and cut into 2-inch pieces
4 ounces sliced white button mushrooms
4 large cloves garlic, minced
1/4 teaspoon crushed red pepper flakes
1 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
2 tablespoons olive oil
3/4 cup frozen peas
1 small handful fresh parsley, chopped (about 1/2 cup chopped)
1/4 cup heavy whipping cream (sub in cream cheese 1/2 the amount and/or milk/corn starch 1/4 cup milk to 1.5 tsp corn starch)
2 tablespoons grated Parmesan cheese
2 teaspoons freshly grated lemon zest
Additional salt and pepper to taste
Additional Parmesan cheese for serving, if desired

Add the broth, linguine, onion, broccoli, asparagus, mushrooms, garlic, red pepper flakes, salt and pepper to a large pot set over high heat. Drizzle the olive oil over the top.
As soon as it comes to a boil, set the timer for 7 minutes and start tossing constantly with long-handled tongs.
Continue boiling and tossing. As soon as the 7 minutes is up, add the peas, parsley, heavy whipping cream, Parmesan, and lemon zest and continue cooking, tossing constantly, for 1-2 more minutes, until the pasta and veggies appear tender. Remove from heat.
Note that much of the liquid will have evaporated, but not all. And that's okay! Let the pasta sit for a couple of minutes to cool; the sauce will continue to thicken during that time. Taste and add additional salt and pepper if desired. Garnish with additional Parmesan cheese.