Bring a large pot of water to a boil for noodles.
Brown your ground beef in a pan over medium heat.
Rinse and drain ground beef. Place back in pan and add sauce. Simmer.
In a bowl, combine your ricotta and your 3 cups of your mozzarella. Stir until well combined. Set aside.
Once your water is boiling, add salt to the water, then shells. Cook for less time than the directions on package. You want them a little hard. I cooked mine for 5 minutes but the box called for 8-9 minutes. It's okay since you're placing them in the oven after, so they will soften up more.
Rinse the pasta, (this is something I normally never do but with this recipe I find it helps to make the noodles more workable, and if you use cool water the noodles can be handled right away) and set aside.
Now preheat your oven to 400 degrees.
Take a 9 x 13 pan and spray it with non stick spray.
Spoon in a nice layer of sauce on the bottom of the pan.
Now start stuffing your shells. You want to hold it on one hand and use a spoon to transfer the cheese mixture into them. Fill them up, cheese is one of life's little pleasures. Lay them all face up in the pan until the pan is full.
Now sprinkle the remaining 2 cups of mozzarella over top.
Place in the preheated oven for about 15 to 20 minutes.
Serve with a big old cheesy smile!