Use kitchen scissors to cut a sausage down the side. Do not remove the casing. Put a mozzarella stick inside the sausage and press it back into its shape. Put it casing side down in an 8 x 10-inch baking pan. Repeat with the remaining sausage.
Pour the marinara sauce over the sausage.
Bake for 30-40 minutes until the sausage is 160 when checked with a meat thermometer.
Video
Notes
Any type of sausage with a casing will work. Turkey, Pork, Chicken, whichever you prefer is fine. It just needs the casing to hold it together.