Preheat oven to 375 degrees F.
Heat the oil in a saute pan over medium heat. Add onions and cook stirring occasionally, 4 to 5 minutes. Add garlic and cook an additional 3 to 4 minutes, or until onions are light golden but not browned. Remove from heat and cool.
In the bowl of a food processor combine artichoke hearts, spinach, sour cream, mayonnaise, Neufchatel, mozzarella and salt and pepper. Process until smooth. Add cooled onion-garlic mixture to the food processor and pulse a few times to combine.
Transfer mixture into an 8-inch glass square baking dish or 9-inch glass pie plate which has been lightly sprayed with cooking spray. Bake for 15 to 20 minutes or until heated through. Serve with pita wedges or crudites.