Squeeze spinach to remove liquid. In a medium bowl combine spinach, mayonnaise, cream cheese, onion, garlic, parmesan, and pepper. With hand mixer, beat ingredients at MEDIUM speed until well blended, about one minute.
Spoon the mixture into a 3- or 4-cup baking dish that has been sprayed with vegetable spray. Sprinkle evenly with paprika. Bake at 350°F until hot in center and lightly browned on top, about 25 to 30 minutes. Serve hot to spread on baguette slices.