Preheat the oven to 375 degrees F (191 degrees C). Line a baking sheet with parchment paper.
Cut each banana pepper into half lengthwise. Remove the seeds and white flesh from the center. Arrange them on the prepared baking sheet, open side up.
Heat the olive oil in a large skillet over medium-high heat. Add the Italian sausage and cook for 8-10 minutes, breaking apart with a spatula, until browned.
Reduce heat to medium. Add minced garlic and stir for 1 minute, until fragrant.
Stir in diced tomatoes and fresh parsley. Cook for about 2 minutes, until the tomatoes are soft.
Stir in the cream cheese, breaking apart with a meat chopper or wooden spoon. Stir in the parmesan cheese, and season with salt and pepper to your taste.
Fill banana peppers with the sausage filling. Top with shredded mozzarella cheese.
Bake stuffed banana peppers for 18-20 minutes, until the peppers are soft and the cheese is melted and golden.
