Bring a large pot of salted water to a boil. Cook pasta until al dente. Reserve 1 cup of pasta water, then drain pasta.
Meanwhile, heat olive oil in a large saucepan over medium heat. Add shallots and cook until softened, about 2 minutes. Stir in garlic and cook until fragrant, about 30 seconds.
Add tomato paste and red pepper flakes. Cook, stirring frequently, until paste darkens and begins to stick to the pan, 3 to 5 minutes.
If using vodka, add now to deglaze, scraping up browned bits. Simmer until alcohol cooks off, 5 to 7 minutes.
Stir in cream and cook until sauce is smooth and slightly thickened, 2 to 3 minutes. Add lemon juice, salt, and pepper to taste.
Add drained pasta to sauce and toss to coat, adding reserved pasta water 1 to 2 tablespoons at a time until sauce clings to pasta.
Top with fresh basil and parmesan cheese and serve hot.
Notes
Deglaze with vodka to add depth of flavor to the sauce. (Vodka is optional, but recommended.)
Balance the flavors with a pinch of sugar to enhance the savory flavors.
Adjust the spice level by adding as much red pepper flakes as desired.
Cook the pasta al dente in well-salted water.
Use a starchy pasta like rigatoni or penne to thicken the sauce.
Reserve some of the pasta water to add to the sauce if it gets too thick.