Cook pasta according to the package directions in a large pot of boiling water. Drain, rinse with cold water, and set aside.
Brown the sausage in a large skillet over medium heat. When the meat is cooked through, drain the fat from the pan and remove the pan from heat.
Allow the sausage to cool slightly, then transfer it to a large freezer bag.
Add the onion, garlic, tomatoes, cream, and spinach to the bag. Use your fingers to squish the ingredients inside the bag to break the tomatoes into smaller pieces and combine the sauce ingredients.
Add the cooked pasta, then seal the bag and shake to combine.
Open the corner of the bag to remove the excess air. Reseal and freeze.
Cooking Instructions:
Thaw.
Dump in a greased casserole dish and cover the pan with foil or a lid.
Bake, covered at 350° for 40 minutes, until the sauce is bubbly.