Lasagna-Style Baked Ziti

1 lb ziti
1 Tbsp olive oil
1 large yellow onion, diced
3/4 tsp salt
1/4 tsp pepper
1 lb lean ground beef
3 cloves garlic, minced
1/2 c chopped fresh oregano (optional)
1 (26 oz) jar pasta sauce
1/2 c (2 oz) grated Parmesan
1 (15 oz) container ricotta
1 (10 oz) box frozen spinach, thawed and squeezed to remove liquid
1 c grated mozzarella

Cook ziti according to package direction.

Heat oven to 400 degrees. IN a large pot, over medium-low heat, heat oil. Add onion, salt and pepper. Cover and cook until onion is softened, 5-7 minutes. Add beef; increase heat to medium-high and cook until no trace of pink remains, 5-8 minutes. Drain any remaining liquid.

Add garlic and oregano (if using) and cook for 2 minutes. Add pasta sauce and heat for 3 minutes. Remove from heat. Add cooked pasta and toss to coat. Add Parmesan, ricotta and spinach and toss again.

Spread the mixture into a 9"x13" baking dish or individual ramekins and sprinkle with mozzarella. Bake until mozzarella melts, about 15 minutes.

NOTES
From Real Simple.
Untried.