Preheat the oven to 350 degrees.
Start by gathering all of the ingredients. You'll want to take the cream cheese out ahead of time to soften it. Also, slice the banana peppers in half, remove the seeds, and then chop them into small pieces.
Place the cream cheese, sour cream, gorgonzola cheese, and parmesan cheese in a large mixing bowl. Set the bowl aside.
Heat the olive oil in a large skillet, and cook the Italian sausage until no longer pink, about 5-7 minutes. Break the sausage into small pieces as it cooks. Drain excess grease.
Place the cooked sausage on the cream cheese and other ingredients in the bowl.
In the same sauté pan, heat the rest of the olive oil and cook the banana peppers until they soften about 3-4 minutes. Drain any extra liquid.
Stir the garlic in with the peppers and cook for another 2 minutes until the garlic becomes fragrant.
Pour the banana peppers and garlic into the bowl with the sausage.
Using a large spoon or a hand mixer, mix the ingredients.
Give the sausage dip a taste for salt. If needed, start with 1/4 teaspoon and add more until you get the desired flavor.
Spread the Italian sausage dip mixture into a 9-inch casserole dish or baking dish.
Cover the dish with foil and bake in the preheated oven for 30 minutes. Remove the foil and continue cooking for another 10 minutes or until the top is golden brown.
Remove the dip from the oven and let it rest for about 5-10 minutes; this helps the dip firm and thicken up.
Serve in the baking dish or place into a serving bowl.