Boil salted water, cook fettuccine until al dente (10–12 min), drain, and set aside.
Melt butter with olive oil over medium heat, sauté garlic 1–2 min until fragrant.
Add cream, simmer, stir in Parmesan until melted and thickened. Season with salt, pepper, and red pepper flakes.
Stir in lobster, drizzle lemon juice, cook 1–2 min until just heated through.
Toss pasta in sauce until coated.
Top with parsley, serve hot.