Heat the chicken and Italian dressing in a 12-inch cast iron skillet set over medium high heat. Season chicken with salt and pepper to taste.: Steam rises immediately and you will hear an encouraging sizzle as the chicken hits the hot skillet, carrying dressing flavors into the meat. The aroma of toasted herbs and oil will develop quickly, signaling good contact between meat and pan. This initial sear seals juices and creates Maillard browning which deepens flavor, so resist constant stirring. A common mistake is using low heat which prevents proper browning, leaving the chicken pale and less flavorful. If your pan seems crowded, remove a few pieces to keep the surface temperature high and achieve that crisp edge.
Cook chicken until browned and just cooked through, about 5 minutes depending on thickness of chicken.: As the chicken cooks you will notice the edges turn golden and the center lose its raw translucence, producing a concentrated, savory smell. Touch a piece to check firmness, or use a thermometer for precision. Browning provides depth that the sauce will amplify, so aim for color without overcooking which causes dryness. A frequent oversight is letting the chicken sit too long and become chalky, so remove it the moment it is opaque with a small center spring.
Add the box of pasta and the entire jar of marinara. Fill the empty marinara jar with water and add to the skillet. If using a stockpot, use 2 cups water. Lightly stir the mixture to combine.: When you add the pasta and marinara the skillet fills with a rich tomato fragrance and the surface begins to shimmer. The water released from the jar helps the pasta hydrate evenly, while the sauce clings to the ridges of the rigatoni. Stir gently so the pieces are submerged and evenly distributed. Avoid pouring excessive water which will thin the sauce and flatten flavor; aim for enough to just cover the pasta. A mistake here is skipping the rinsing of the jar or mismeasuring water, which can change cooking time and texture.
Bring mixture to a boil and then reduce to a simmer. Cover and cook for 15 minutes or until pasta is tender to your liking.: The pot will sing with rolling bubbles at first, then settle into a quieter simmer once covered. Steam will fog the skillet and aromas intensify. Simmering lets the pasta absorb tomato flavor slowly, and the starch released helps thicken the sauce, creating a cohesive finish. Check for tenderness around 12 minutes to avoid over softening; the centers should be just chewy. A typical misstep is keeping a vigorous boil which can break down pasta and burn the sauce around the edges.
Cover with grated Parmesan and then shredded mozzarella. No need to stir. Continue to cook for 2-3 more minutes or until cheese is fully melted. You can also broil the entire skillet for about 4 minutes to make the cheese extra melty!: The moment you add the cheeses the kitchen fills with a rich, milky scent as they begin to melt into glossy ribbons. Parmesan will melt into savory pockets while mozzarella forms a stretchy blanket on top. Leaving the cheese undisturbed allows pockets of steam to soften it evenly into a luscious layer. If you choose to broil, watch closely so the top turns golden rather than black. A common error is stirring in the cheese at high heat which can make it oily and break the desired texture.
Top with chopped basil (optional) and serve! Enjoy!: The fresh basil adds a bright herbal perfume and visual contrast, releasing citrusy notes when scattered over hot cheese. The sizzling of the skillet will soften the leaves slightly while preserving color. Serve directly from the pan for a rustic presentation, allowing diners to spoon portions with both saucy and crisp edges. One mistake to avoid is adding the basil too early, which wilts it into anonymity; add just before serving for maximum freshness.