Greek Lasagna

9 lasagna noodles
8 ounces lean ground beef
1/2 cup chopped yellow onion
1/2 (10 ounce) package frozen, chopped spinach, squeezed dry
1 cup part-skim ricotta cheese
1/4 cup feta cheese, crumbled
1/4 cup sliced pitted black olives
3 tablespoons chopped fresh mint, divided
1 1/2 cups reduced sodium tomato sauce
Salt and pepper to taste

Preheat oven to 375 degrees F. Spray a medium baking dish with vegetable cooking spray; set aside.

Cook noodles according to package directions, but do not add salt. Drain.
Meanwhile, spray a medium nonstick skillet with vegetable cooking spray. Heat over medium heat. Add beef and onion. Cook, stirring, until browned, about 5 minutes. Place mixture on a paper towel-lined plate; drain.
In a medium bowl, combine spinach, ricotta cheese, feta cheese, olives and 2 tablespoons mint. Spread 1/2 cup tomato sauce in prepared dish. Top with 3 noodles. Spread some spinach mixture over noodles. Top with some beef mixture. Spoon 1/4 cup tomato sauce over beef mixture. Continue layering with remaining noodles, spinach mixture, beef mixture, and sauce. Cover with foil. Bake until filling is heated through, about 30 minutes.
Sprinkle with remaining mint. Serve immediately.