Get the Filling Ready: Cook the ground beef in a pan over medium heat until it is browned. While the garlic is beginning to release its aroma, mix in the dried oregano and minced garlic. Take it off the stove and let it cool for a while. After the beef mixture has cooled, stir in the ricotta, mozzarella, Pecorino Romano, beaten egg, salt, and pepper in a bowl. Blend well by mixing.
Load and Put Together: Distribute 1 cup of the basil-tomato sauce evenly on the base of a baking dish. Arrange the cooked pasta shells in a tight fashion in the dish and fill each one with the meat and cheese mixture. Distribute the leftover tomato basil sauce equally among the shells. On top, sprinkle the last half cup of mozzarella.
Put it in the oven and bake it for 25 minutes with the foil on top. Once the cheese begins to bubble and become golden, take it out of the oven and continue baking for another 10 minutes.
Before serving, take it out of the oven and give it a little cooling. Warm the dish before serving and top with minced parsley.
About fifty-five minutes total, including twenty minutes for preparation, and six servings from the finished product.
