Cook ziti pasta according to package instructions until al dente, drain and set aside.
In a large skillet, heat olive oil over medium heat. Add Italian sausage, breaking apart with a spoon, and cook until browned and cooked through, about 7-8 minutes. Drain excess fat.
Mix cooked sausage with marinara sauce, garlic powder, black pepper, and dried oregano.
In a large bowl, combine cooked pasta, sausage sauce mixture, and ricotta cheese.
Transfer mixture to a greased 9x13 inch baking dish. Top with shredded mozzarella and grated Parmesan cheese.
Bake uncovered for 25-30 minutes until cheese is melted and bubbly.
Let stand for 5 minutes before serving.
Notes
For extra flavor, add fresh basil or a pinch of red pepper flakes before baking.