Cook the pasta: Boil the ziti in salted water until just shy of al dente, about 8 minutes. Drain and set aside; it will finish cooking in the oven.
Mix the ricotta filling: In a bowl, stir together the ricotta, egg, Parmesan, Romano, Italian seasoning, salt and pepper until smooth and evenly combined.
Warm the sauce: Heat olive oil in a saucepan over medium heat and cook the garlic for about 1 minute until fragrant. Stir in the marinara sauce and simmer for 5 minutes.
Combine pasta and sauce: Toss the drained pasta with the warm marinara sauce until every piece is coated.
Layer the first half: Spread half of the sauced pasta into a greased 9x13-inch baking dish, spreading it into an even layer.
Add the ricotta layer: Spoon the ricotta mixture evenly over the pasta, then sprinkle with half of the mozzarella and fontina.
Top with remaining pasta: Spread the rest of the sauced pasta over the cheese layer, pressing gently to even it out.
Finish with cheese: Scatter the remaining mozzarella and fontina over the top so the surface is fully covered.
Bake covered: Cover the dish tightly with foil and bake at 375°F for 20 minutes, allowing the layers to heat through.
Bake uncovered: Remove the foil and bake for another 10 to 15 minutes, until the top turns golden and the edges bubble.
Rest before serving: Let the dish rest for 10 minutes so the layers set and slice cleanly.
Garnish and serve: Sprinkle with chopped fresh parsley and serve warm straight from the baking dish.