Preheat the oven to 350 degrees F (175 degrees C). Lightly grease a glass pie plate.
In a medium bowl, mix together the hearts of palm, mozzarella cheese, Parmesan cheese, green onion, sour cream and mayonnaise. Spread into the greased pie plate.
Bake uncovered for 20 minutes, or until light brown and bubbly. Serve with crackers or Melba rounds.