Timballo Spaghetti Casserole - cooking recipe

Ingredients

1 tablespoon olive oil
1 (16 ounce) package spaghetti
2 (24 ounce) jars marinara sauce
3 cups cooked chicken breast meat, diced
1 large onion, diced
1 (7 ounce) package of sliced pepperoni, diced
1 green pepper, diced
1 (5 ounce) can mushroom pieces, drained
1 (3 ounce) can sliced black olives, drained
3 cups shredded mozzarella cheese
1 tablespoon grated Parmesan cheese, or to taste

Preparation

Preheat oven to 350 degrees F (175 degrees C). Spread olive oil into the bottom of a cast-iron skillet or large baking dish.
Bring a large pot of lightly salted water to a boil. Cook spaghetti in the boiling water, stirring occasionally until cooked through but firm to the bite, about 12 minutes; drain.
Stir spaghetti, marinara sauce, diced chicken, onion, pepperoni, green pepper, mushroom pieces, and black olives together in a large bowl; transfer into the prepared cast-iron skillet. Top with mozzarella cheese in a layer and sprinkle with Parmesan cheese.
Bake in the preheated oven until casserole is bubbling, chicken is cooked through, and the cheese topping is lightly browned, about 30 minutes.