Preheat the oven to 350°F. Spray a 9x13 baking dish with non-stick cooking spray.
Cook the pasta according to package directions for al dente consistency. Drain and return to the pot. Set aside.
In a large bowl, stir together the spinach dip, oat milk, bell pepper, Italian seasoning, garlic salt, and 1/2 cup mozzarella cheese.
Pour the spinach dip mixture into the pot with the cooked pasta. Stir to coat.
Pour the entire pasta mixture into the prepared baking dish. Sprinkle with the remaining mozzarella cheese.
Bake for 20 minutes, until cheese is melted, then serve hot.