If using fresh lobster, boil in salted water for 8-10 minutes until bright red. Cool and chop meat. If using pre-cooked lobster, chop and set aside.
Bring a large pot of salted water to a boil. Cook bucatini according to package instructions for 8-10 minutes until al dente. Reserve 1 cup of pasta water, drain, and set aside.
In a large skillet, heat olive oil and unsalted butter over medium heat. Add minced garlic and red pepper flakes, sauté for 1 minute until fragrant.
Add chopped lobster meat and halved cherry tomatoes to the skillet. Cook for 2-3 minutes until tomatoes soften. Add drained bucatini, tossing gently. Gradually pour in reserved pasta water until desired sauce consistency is reached.
Stir in chopped parsley, grated Parmesan cheese, and lemon juice. Season with salt and pepper to taste. Serve immediately, garnished with extra parsley and Parmesan if desired.