Spaghetti all'Assassina (Assassin's Spaghetti)

Make the broth - Add 4 cups water to a medium saucepan and bring it to a boil. Add about 1/3 of the tomato purée and the tomato paste to the water and whisk to combine. Season with 1 teaspoon kosher salt. Reduce the heat to low to keep the broth hot.

Assemble the sauce - Meanwhile, heat a 10 to 12-inch cast-iron or non-stick skillet (wide enough to fit the spaghetti lying completely flat) over medium-high heat. Add the oil. Once hot, add the garlic and chili flakes and cook just until fragrant, about 30 seconds. Add the rest of the tomato purée and stir. Season with salt to taste.

Start cooking the pasta - Add the pasta, spreading it out as much as you can to submerge it in sauce. If needed, add up to a cup of the broth to just barely submerge the noodles. The heat should remain on medium-high. Cook, undisturbed, until charred in places on the bottom and the sauce is looking dry, about 5 minutes.

Flip the pasta - Once the pasta has formed some burnt crust on the bottom, use a wooden spatula to scrape it up and flip it over so the charred bits are on top. Spread it out as best you can and reduce the heat to medium. Add 2 to 3 ladlefuls of the broth on top, barely submerging the noodles and moving the pasta around a bit so the liquid can penetrate the strands. It should be simmering. As the liquid evaporates and the pasta begins to peek out from the sauce, add more broth to keep it barely covered, nudging the pasta around the pan periodically with a spatula to ensure it cooks evenly.

Test the pasta - Once the pasta has become flexible and has been cooking for at least 10 minutes, start moving it around the pan more. Give it a taste. You want it to be al dente with a bit of chew with a thick, well-coated sauce. If needed, add salt and a pinch of sugar to balance the flavors. The total cook time will likely be somewhere around 20 minutes (ignore the package instructions!), but use your senses to decide. If your sauce isn't thick enough—it should be thick and clinging to the noodles but not completely dry—let it bubble for a minute or two, then transfer the pasta to a serving plate and serve hot.