Preheat oven to 400 degrees F.
Cook pasta according to package directions until al dente. Drain, do not rinse.
Meanwhile, in a medium pot, add the pasta sauce, diced tomatoes, and ricotta. Stir to combine.
Simmer over low heat until just heated through.
To an 8x8 glass baking dish, add 1/3 sauce/ricotta mixture. Spread evenly across the bottom.
Next, add 1/2 of the cooked pasta to the baking dish and another 1/3 of the sauce, evenly over the pasta.
Top the sauce with the first portion of the shredded cheese.
Next, add the rest of the pasta, then sauce, then top with remaining cheese.
Sprinkle oregano across the top of the ziti
For easy clean up, line a baking sheet with foil. Place ziti on baking sheet and bake for 25-30 minutes, or until the cheese has melted.
For a crispier top, broil on high for an additional 1-2 minutes.
Remove from oven and let rest for 10 minutes before serving.