Start with the aromatics: Place a large pot or deep skillet over medium heat and add the olive oil. Once warm, add the chopped onion and cook for several minutes, stirring often, until it softens and turns lightly golden. Add the minced garlic and cook briefly until fragrant, keeping an eye on it so it does not brown.
Build the base flavor: Stir in the Italian seasoning and red pepper flakes, letting them toast gently in the oil for about 30 seconds. This step wakes up the spices and gives the whole dish a deeper flavor right from the start.
Add tomatoes and broth: Pour in the chicken broth, then add the halved cherry tomatoes. Season lightly with salt and pepper. Stir everything together and bring the mixture to a gentle boil, allowing the tomatoes to soften slightly as the liquid heats.
Add the pasta: Break the linguine in half and lay it into the pot, pressing it down so it sits under the liquid. Stir gently to separate the strands and make sure they are mostly covered by the broth.
Let it cook: Reduce the heat to medium and let the pasta simmer uncovered. Stir every minute or so to prevent sticking. As it cooks, the pasta will absorb the broth and release starch, creating a light sauce. This usually takes about 10 to 12 minutes.
Finish with cheese: Once the pasta reaches your preferred tenderness and most of the liquid has thickened, turn off the heat. Sprinkle in the Parmesan cheese and stir until it melts smoothly into the sauce, coating every strand.
Add fresh herbs: Scatter the chopped basil over the pasta and give it one final gentle stir. Taste and adjust seasoning with more salt, pepper, or red pepper flakes if needed.
Rest briefly and serve: Let the pasta sit for a minute or two before serving. This helps the sauce settle and cling to the noodles even better.
