Preheat the oven to 375 degrees Fahrenheit. Add the pasta shells to a pot of salted, boiling water and cook for two minutes short of al dente according to package instructions. (i.e., If the directions say to cook for 12 minutes, then cook for 10 minutes instead.) Drain and let cool slightly so they can be handled without burning your hands.

Meanwhile, mix the ricotta, ¾ cup of the shredded mozzarella, Parmesan, minced garlic, spinach, salt, and pepper until well combined.

Carefully stuff each pasta shell with the ricotta mixture. You can use a spoon, a Ziplock bag with a hole cut in the bottom corner like a piping bag, or a piping bag if you have one.

Pour the marinara into an 8 inch by 11 inch or 9 inch by 13 inch casserole dish or a large skillet, spreading evenly. Filling the dish too full may cause bubbling over in the oven, so just keep it 1 - 2 inches below the rim.

Lay the stuffed shells seam-side up in the sauce. Once all of the shells are in the dish, sprinkle the remaining ¾ cup of mozzarella over the top.

Cover the pan with foil and bake for 25 minutes, then remove the foil and broil for 2 - 3 minutes or until golden brown on top. Let cool for about 5 - 10 minutes, top with fresh basil, and enjoy!