Heat olive oil in a heavy skillet over medium heat until it shimmers slightly—you'll see ripples move when you tilt the pan. Add diced onion and cook until the edges turn translucent, about four minutes, then add garlic and stir constantly for exactly one minute because garlic burns fast and bitter garlic ruins everything.

Stir in oregano, basil, and black pepper, letting them bloom in the oil for thirty seconds—this releases their essential oils so they actually flavor the sauce instead of just sitting there dry. Pour in crushed tomatoes and water, then simmer uncovered for twelve minutes while you get the pasta going.

Cook ziti to one minute under al dente because it'll finish cooking in the oven—I learned this the hard way when Marco bit into mushy pasta at my dinner party two years ago and said nothing but his expression said everything. Drain and set aside in a large bowl without rinsing it.

While the pasta's still warm, stir in ricotta, shredded chicken, one cup mozzarella, and half the Parmesan cheese, mixing gently so you don't mash the pasta tubes. The warmth helps ricotta distribute evenly, which won't happen if you wait until everything cools—this is the secret most recipes miss entirely.

Pour the tomato sauce into the pasta mixture and fold everything together until each piece gets coated. Transfer to a greased 9x13 baking dish, spreading it into one even layer so nothing sits in a dense pocket at the bottom.

Sprinkle remaining mozzarella and Parmesan over the top, then bake uncovered at 375°F for twenty-five minutes until the cheese on top turns golden but hasn't started browning. Cover with foil and bake another fifteen minutes so the center heats through without the top burning—I learned to do this after a dinner party disaster where the edges carbonized while the middle stayed lukewarm.

Let the baking dish rest for five minutes before serving because cutting into it immediately causes the filling to slide everywhere. Garnish with fresh parsley right before plating so it stays bright green instead of turning dark.