Preheat oven to 375°F and spray an 11×9-inch casserole dish with nonstick cooking spray.: As the oven warms, you'll smell that warm, dry heat that signals the right environment for a crisp, bubbling top. Preheating ensures even baking so the interior reaches temperature at the same pace as the surface browns. Lightly spraying the dish prevents sticking and helps lift servings cleanly, avoid using too much oil which can pool and create grease spots on the top.
In a large saucepan, boil the pasta according to package instructions (al dente/no salt), and drain.: The water will come to a lively boil, and as the ziti pasta cooks you can hear it shifting in the pot. Cook to al dente so the tubes hold their shape during baking and remain slightly firm to the bite. Rinsing after draining is a common pitfall that washes away starches that help the sauce cling; avoid rinsing unless you need to stop cooking immediately.
In the same large saucepan set over medium heat, cook the marinara sauce and cream cheese together until the cheese melts. Stir often.: As you stir, the cream cheese will soften and blend into the marinara sauce , releasing steam and a rich, tangy aroma. The mixture should be smooth and slightly glossy, signaling full incorporation. Keep the heat moderate, because too high a temperature can cause the dairy to separate and become grainy, which will affect the sauce texture.
Add the pasta to the marinara/cheese sauce and mix well.: The ziti pasta will soak up the sauce slightly, and you should see each tube well coated with glossy sauce. Mixing thoroughly ensures even seasoning and prevents dry pockets in the casserole. A mistake here is folding too roughly, which can break the pasta; be gentle but thorough.
Pour half the marinara/cheese/ziti sauce in the prepared baking dish and sprinkle with half the mozzarella and half the Parmesan cheeses.: As the first layer settles, the cheeses will create a melty contrast when baked, and you may hear a faint sizzle as residual heat meets the cheese. This layering builds pockets of melty cheese and flavor; skipping layers can lead to an uneven bake where some areas lack cheese coverage.
Sprinkle the cheeses with 2 tablespoons chopped fresh basil.: The fresh basil adds an aromatic lift between layers, releasing a green, herbaceous perfume when warmed. This middle sprinkle keeps the herb flavor consistent through the dish instead of only on the top. Avoid chopping basil too far in advance since it wilts and loses fragrance quickly.
Layer the remaining marinara/cheese/ziti sauce over the cheese and top with the remaining mozzarella and Parmesan.: The top layer of cheeses is what will form the browned, bubbly surface, so distribute them evenly for consistent browning and melt. You should see an even blanket of cheese that will blister and brown in the oven. Piling cheese into one spot can lead to uneven melting and overly greasy patches.
Cover and bake at 375°F for 30 minutes.: Covering traps steam and allows the casserole to heat through without drying out, so the interior becomes uniformly hot and the sauce melds with the pasta . You might hear a gentle bubbling under the foil, which indicates internal warming. Leaving it uncovered too early can dry the edges before the center is fully heated.
Remove the cover and bake an additional 15-20 minutes or until the baked ziti is bubbly and cheese is golden.: When you remove the cover, the surface will go from soft to a crisp, golden finish, and you may notice a toasty, savory aroma as the cheeses brown. This step creates the signature texture contrast, and watch closely so the cheese does not burn; ovens vary, so lean toward the lower time and extend if needed.
Garnish with the remaining chopped basil.: Fresh basil scattered at the end adds a bright scent and visual pop against the golden top, offering a fresh counterpoint to the rich, baked flavors. Adding it hot releases fragrant oils, enhancing each bite. Be careful to add basil too early and it will wilt into the dish, losing its fresh snap.