With a knife or kitchen scissors, make a slice down one side of each sausage, cutting about halfway into the sausage but not all the way through.
Place a mozzarella stick into each cut, then using your hands, gently press sausage back into shape.
Pour marinara into the bottom of a baking dish and spread out with a spoon or spatula.
Arrange sausages in the baking dish, cut side up. Cover with foil and bake 30 minutes. Uncover and bake 10 minutes more, until sausages are cooked through and cheese is bubbly and lightly golden in places. Enjoy!
