Slice each sausage link lengthwise and press them flat.

Heat a pan over medium heat and cook the sausages on both sides until fully done. Remove them from the pan but leave any grease behind.

In the same pan, add the sliced peppers and onions along with the balsamic vinegar. Cook until the vegetables soften and caramelize.

Once done, take the vegetables off the heat and set them aside.

Place the cooked sausages in a baking dish, then top them with the pepper and onion mixture. Layer with provolone and shredded mozzarella.

Set your oven to broil and place the dish inside until the cheese is melted and bubbly. Serve hot and enjoy!