Start by boiling a large pot of salted water. Add in your spaghetti and cook according to package instructions until al dente. Remember to stir occasionally to prevent sticking. Once done, reserve about a cup of pasta water, then drain the rest.

In a large skillet, heat the olive oil over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes. Then, toss in the garlic and red chili flakes. Sauté for an additional minute until fragrant, but be careful not to burn the garlic.

Now it’s time for the stars of the show: the tomatoes. Pour in the puréed San Marzano tomatoes while stirring. Add the salt and pepper. Let this simmer for about 10 minutes, allowing the flavors to meld beautifully.

As the sauce simmers, toss in the reserved pasta water as needed to achieve your desired sauce consistency. Add the butter, stirring until it melts, and then incorporate the fresh basil and lemon zest.

Once your sauce is ready, add the drained spaghetti directly into the sauce. Toss well to ensure every strand is coated. If the pasta appears dry, add more reserved pasta water.

Plate the pasta, sprinkling the freshly grated Parmigiano-Reggiano on top. Garnish with extra basil leaves. You’re ready to dig in!