Boil the pasta according to package instructions (al dente). Add 1 tablespoon of olive oil to pasta water.
Once cooked add pasta to a large mixing bowl, add tuna, marinara sauce, 1 teaspoon of oregano, garlic powder. Mix to combine.
In a 9 x 13-inch baking dish add half of the pasta mix, add a layer of half of the cheese, another pasta layer, and top with olives and tomatoes. Sprinkle 1 teaspoon of oregano and finish with a layer of remaining cheese.
Bake at 400 F for about 20 minutes or until cheese is properly melted.
Garnish with fresh herbs and more oregano!