Set a large skillet onto a stove with medium-high heat and heat some olive oil in it. Plop the cabbage and onion into the heated oil. Leave for about 8-10 minutes or until the vegetables tender.
Chop the sausage into bite-sized pieces. Mix in with the cabbage and onion and leave for another 8 minutes.
Spread the shredded mozzarella on top before turning off the heat. Cover with the lid and let it stand for 5 more minutes to melt the cheese. Afterwards, remove the lid and mix. Garnish with some salt, pepper, and parsley before serving.