Cook pasta in salted water until just under al dente. Drain, reserving a little pasta water, then set aside.
In a large skillet, heat a splash of olive oil (plus a little butter, if desired). Cook diced onion until translucent, then add garlic and cook until fragrant (~1 min).
Toss in halved cherry tomatoes, seasoning with salt & pepper. Sauté until they begin to soften (~4 min).
Stir in thawed, rinsed langostino tails and heat through (~2 min).
Pour in the full container of lobster bisque. Sprinkle in red pepper flakes (optional), then squeeze in lemon juice/zest. Stir to combine and heat the sauce.
Add your drained pasta to the sauce, tossing to coat. Add a splash of reserved pasta water—the starch helps it cling.
Stir in a generous amount of grated Parmesan. Garnish with fresh parsley or basil, extra red-pepper flakes, and more Parmesan. Serve hot.
