In a large skillet, cook the Italian sausage over medium heat until browned and cooked through, about 5-7 minutes. Use a spatula to break up the sausage into small pieces as it cooks.
Once cooked, drain any excess fat from the skillet and remove it from heat. Allow the sausage to cool slightly.
In a mixing bowl, combine the softened cream cheese, shredded cheddar cheese, shredded mozzarella cheese, sour cream, diced green onions, jalapeños (if using), garlic powder, onion powder, salt, and pepper. Mix until well combined.
Fold the cooked sausage into the cheese mixture until evenly distributed.
Transfer the mixture into an oven-safe baking dish and spread it out evenly.
Preheat your oven to 350°F (175°C). Bake the dip for about 20 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let it cool for a few minutes before serving. Serve warm with tortilla chips or bread for dipping.