Cut an inch off the stems. Place them in a baking dish or in a cast iron skillet. Drizzle olive oil on them and sprinkle salt. Mix them with your hand so that they are evenly coated.
Bake for 20-25 minutes until tender. Remove from oven. Top them with shredded mozzarella and bake until the cheese melts and gets slightly golden, for about 3 minutes.