Bring a large pot of generously salted water to a rolling boil. Add the linguine or fettuccine and cook according to package directions until al dente. Before draining, reserve 1 to 1.5 cups of the pasta cooking water. Drain the pasta and set aside.

While the pasta cooks, heat olive oil and unsalted butter in a large skillet or Dutch oven over medium heat. Add the finely minced shallot and cook until softened, about 2-3 minutes. Add the minced garlic and red pepper flakes (if using), and cook for another minute until fragrant, being careful not to burn the garlic.

Add the peeled and deveined shrimp to the skillet. Season with salt and black pepper. Cook for 2-3 minutes, stirring occasionally, until the shrimp turn pink and opaque. Do not overcook. Remove the cooked shrimp from the skillet and set aside.

Pour both cartons of Trader Joe's Lobster Bisque into the same skillet. Bring the bisque to a gentle simmer, stirring occasionally. If using, whisk in the heavy cream for an even richer sauce. Let it simmer gently for 3-5 minutes to allow the flavors to meld and the sauce to warm through completely.

Add the drained pasta directly to the skillet with the bisque sauce. Using tongs, toss the pasta well to coat it evenly with the sauce. If the sauce appears too thick, add reserved pasta water, a quarter cup at a time, until it reaches your desired consistency.

Return the cooked shrimp to the skillet and gently toss with the pasta and sauce, just enough to warm the shrimp through. Garnish generously with fresh chopped parsley. Serve immediately, with optional grated Parmesan cheese on the side.