Preheat your oven to 375 degrees Fahrenheit and prepare a 9-inch by 13-inch baking dish by spraying it with cooking spray.
Place the sausages on a cutting board and slice the sausages from end to end, leaving the ends intact so the sausages don't fall open completely.
Mix together the shredded cheeses and Italian seasoning until combined. Stuff about 2/3 of the cheese mixture into the sausages, reserving the rest for topping.
Ladle half the marinara sauce into the bottom of the baking dish and nestle the stuffed sausages into the sauce.
Top the stuffed sausages with the remainder of the marinara sauce and sprinkle the remaining cheese on top.
Bake at 375 degrees Fahrenheit for about 20-25 minutes, or until the sausages are cooked through and the cheese is bubbly and golden brown.
Serve while hot with some fresh chopped basil or parsley (optional).