Preheat your oven to 375°F (190°C).
In a large pot, cook the ziti according to package instructions until al dente, then drain.
While the pasta cooks, heat olive oil in a skillet over medium heat and add the sausage, breaking it apart as it cooks.
Once the sausage is browned and cooked through, stir in the marinara sauce, oregano, garlic powder, salt, and pepper.
In a large mixing bowl, combine the ricotta cheese with half of the mozzarella and half of the Parmesan, mixing well.
Add the drained ziti to the sausage and sauce mixture, stirring to combine thoroughly.
Layer half of the ziti mixture into a baking dish, followed by dollops of the ricotta mixture, then repeat with the remaining ziti and cheeses on top.
Sprinkle the remaining mozzarella and Parmesan on top before placing it in the oven.
Bake uncovered for 25-30 minutes, until the cheese is melted and bubbly.
Let the baked ziti cool for about 10 minutes before serving.