Add the ziti, marinara, 3/4 of the ricotta and half the mozzarella. Stir to combine.
Sprinkle with the remaining mozzarella and dot with the remaining ricotta. Season with the italian seasoning and cover with the lid.
Cook the ziti on high for 2 hours or low for 4-5 hours.
Serve immediately.
Notes
Best if served when ready. Leftover baked ziti can be stored in the refrigerator in an airtight container for up to 3 days. Reheat in the microwave adding extra sauce, if necessary.