Preheat oven to 375°F. Bring a large pot of well-salted water to a boil. Cook ziti 1 minute shy of al dente. Drain and set aside.
Heat a large pot over medium-high heat for 3 to 4 minutes to preheat. Add oil and let it heat up to shimmering hot, another 30 to 60 seconds. Add ground beef and break it up a bit, but let it cook undisturbed until browned and caramelized on the bottom, about 5 minutes. Stir and continue browning until deeply colored.
Add onion, salt, and pepper. Cook until softened, about 5 minutes. Add garlic and cook 30 seconds.
Add tomato paste and cook, stirring frequently, until it darkens and begins sticking to the bottom of the pot, about 3 to 4 minutes (don't rush this, it adds a lot of flavor and color).
Pour in both cans of tomatoes and add the baking soda. Bring to a simmer and cook 15 to 20 minutes, stirring occasionally, until slightly thickened but still loose and saucy. Taste and adjust salt if needed.
In a bowl, mix ricotta, egg, Parmesan, and 1 cup of the mozzarella until smooth.
In a large bowl, combine the cooked ziti with about three-quarters of the beef sauce. The pasta should look generously coated and slightly saucy.
Spread a thin layer of sauce in the bottom of a 9x13 inch baking dish. Add half the pasta mixture, then dollop half the ricotta mixture over the top. Repeat with remaining pasta and ricotta. Spoon remaining sauce over the top.
Sprinkle the 2 1/2 cups mozzarella evenly over the surface. Cover loosely with foil.
Bake 30 minutes covered. Remove foil and bake 15 to 20 minutes more, until bubbling and golden at the edges.
Rest 15 minutes before slicing so the layers set properly. Sprinkle with more parsley before serving.