Preheat oven to 350 degrees fahrenheit.
Bring a large pot of water to a boil. Cook the shells in the water for approximately half of the listed cooking time on the package ( around 6 minutes for the shells I used ).
Cook the spinach according to package directions. Let cool, squeeze the water out.
Mix the garlic, spinach, parsley, basil, ricotta, eggs, half of the parmesan, all of the salt and pepper in a large bowl until well combined.
If you'd like to include the sausage ( SO GOOD! But usually only added as a special treat in my house ), brown it in a pan over medium high heat for 4 - 6 minutes, crumbling it up with a cooking utensil in the pan as it cooks.
Prepare one 8x11 pan and one 9x9 pan ( or a second 8x11 -- I don't have two so I have to cram into my 9x9 ) by pouring the tomato sauce into the bottom of each pan.
Put the filling into the freezer bag, cut 1" off of the corner to make a piping bag. Pipe each shell almost full with filling. Place each filled shell into one of the pans.
Split the remaining cheeses ( mozzarella and parmesan ) between the two dishes -- covering the shells in both dishes with cheese.
Bake for 25 minutes to eat tonight. Freezing directions in "Notes".