Place sausage rings on a baking sheet and liberally drizzle extra-virgin olive oil down over them. Place in hot oven and roast until casings are crisp and juices run clear, somewhere between 15 and 20 minutes. Remove from oven to rest sausages; switch on broiler.
While sausages roast, heat a skillet over medium heat with 3 tablespoons extra-virgin olive oil and sliced garlic. Simmer garlic in extra-virgin olive oil 2 to 3 minutes then add peppers and onions. Turn the heat up a notch, and cook until the vegetables are tender but the peppers still hold strong color, 5 to 6 minutes. Add thinned tomato sauce, salt, and pepper and reduce. Turn heat back to low and hold the veggies until the sausage comes out of the oven, a couple of minutes.
Toast the split bread, remove from oven, rub with cracked garlic, liberally drizzle with extra-virgin olive oil, and cover with cheese and lots of black pepper. Return to the broiler to brown cheese, 1 minute. Scatter parsley over the bread.
Cut bread into chunks and pile with peppers and onions then sausages. The bread will soak in the juices as you work through the sausage, peppers and onions.