Heat pan on med/med high heat. Add 1 tablespoon of olive oil, diced garlic and shallot in pan. Brown garlic and shallot until fragrant and translucent.
Add ground beef to pan and brown. Add frozen spinach, mushrooms and spices to taste. Drain excess oil. Set aside once browned.
In separate pot, boil large pasta shells al dente. (Not all the way cooked, will need to be a little under cooked or they will fall apart) cooking time for us was 10min, check pasta when cooking as to not go over. Once al dente, drain water and set aside.
Add one can of pasta sauce to 9×13 casserole dish.
Fill pasta shells with browned meat. Place cheese on top of shells. We used Oaxaca cheese, but you can use mozzarella or any other cheese you prefer.
Place in oven covered at 375 degrees for 25 minutes. Uncover and place back in oven for another 15 minutes.