In a medium bowl, combine ricotta, cottage cheese, spinach, egg, oregano and black pepper. Cover and refrigerate until ready to use.

Prepare lasagna noodles according to package directions.

Drain and rinse the cooked lasagna noodles with cold water.

Set the lasagna noodles aside.

Remove the skin from the rotisserie chicken.

Chop the chicken meat into bite-sized pieces (about 3 1/2 cups).

Preheat oven to 375°F (190°C).

Spray a 9x13-inch baking pan with cooking spray.

Spoon 1 cup of pasta sauce over the bottom of the prepared baking pan.

Arrange 4 lasagna noodles over the sauce (3 lengthwise, 1 crosswise).

Top the noodles with another 1 cup of pasta sauce.

Sprinkle with 1/3 of the chicken, 1/3 of the feta cheese, 1/3 of the mozzarella cheese, and 1/3 of the olives (if using).

Arrange 4 more lasagna noodles over the cheese and chicken layer.

Top with 1 cup of pasta sauce.

Sprinkle with 1/3 of the chicken, the entire ricotta/spinach mixture, 1/3 of the feta cheese, 1/3 of the mozzarella cheese, and 1/3 of the olives (if using).

Repeat the layering with the remaining noodles, sauce, chicken, feta cheese, mozzarella cheese, and olives (if using).

Sprinkle the chopped fresh parsley over the top.

Cover the baking pan loosely with foil.

Bake at 375°F (190°C) for 40 minutes.

Remove the foil and bake for 5 more minutes.

Let the lasagna stand for 10 minutes before serving.