Follow these simple steps for pasta perfection:

1. Prepare Your Ingredients: Halve the cherry tomatoes, thinly slice the onion and garlic. Gather all other ingredients and have them measured and ready near your stovetop. This makes the assembly process quick and seamless.
2. Combine in Pan: Select a large, wide skillet or Dutch oven with a lid (at least 12 inches in diameter). It needs to be large enough to hold the pasta flat initially and allow for stirring later. Place the uncooked linguine, halved cherry tomatoes, sliced onion, sliced garlic, red pepper flakes, 2 sprigs of basil, and extra virgin olive oil into the pan. Arrange the pasta so it lies relatively flat, though some crisscrossing is fine.
3. Add Liquid and Seasoning: Pour the vegetable or chicken broth over the pasta and other ingredients. Ensure the pasta is mostly submerged. Sprinkle the kosher salt and freshly ground black pepper evenly over the top.
4. Bring to a Boil: Place the pan over high heat and bring the liquid to a vigorous boil. This initial high heat helps the pasta start cooking quickly and prevents sticking.
5. Simmer and Stir: Once boiling, reduce the heat to medium-high or medium to maintain a steady, vigorous simmer. Stir the pasta frequently using tongs, about every 1-2 minutes. This is crucial! Frequent stirring prevents the pasta strands from sticking together and ensures they cook evenly in the liquid. It also helps release the pasta’s starches, which will thicken the sauce.
6. Cook Until Al Dente: Continue simmering and stirring for approximately 9-12 minutes. The exact time will depend on your specific brand of pasta, the heat of your stove, and the dimensions of your pan. Start checking the pasta for doneness around the 8-minute mark. You want it to be cooked through but still have a slight bite (al dente). Most of the liquid should be absorbed or evaporated, leaving behind a light sauce coating the pasta. If the pan seems dry before the pasta is cooked, add a splash more broth or hot water (a few tablespoons at a time). Conversely, if the pasta is cooked but there’s still too much liquid, you can let it simmer for another minute or two with the lid off (if you used one) to reduce further.
7. Wilt the Spinach: Once the pasta is perfectly al dente and coated in a light sauce, remove the pan from the heat. Add the fresh baby spinach directly on top of the hot pasta.
8. Stir in Cheese and Finish: Sprinkle the grated Parmesan cheese over the spinach and pasta. Use your tongs to gently toss everything together. The residual heat from the pasta and sauce will wilt the spinach perfectly within a minute or two, and the cheese will melt into the sauce, making it creamy and luscious.
9. Serve Immediately: Remove the initial basil sprigs (they’ve done their job infusing flavor). Taste and adjust seasoning if necessary, adding more salt, pepper, or red pepper flakes. Divide the pasta among serving bowls, garnish with additional fresh basil leaves and extra grated Parmesan cheese, and serve immediately for the best texture and flavor.