Cut off tops of 6 green peppers; discard tops and seeds. Cook peppers 4 minutes in boiling salted water to cover; drain and set aside.
Sauté ham in butter in a skillet until browned, stirring occasionally. Add onion, green pepper, and garlic; cook over medium heat until tender. Add tomato; simmer over low heat 1 hour, stirring occasionally. Stir in 2 cups breadcrumbs. Add whipping cream, green onion tops, parsley, salt, and pepper; mix well.
Stuff mixture into green peppers; top with remaining breadcrumbs. Place in a lightly greased, shallow baking dish. Bake at 350° for 30 minutes. Serve hot.