In a large bowl, combine the ground beef, breadcrumbs, Parmesan cheese, green onions, egg, garlic, salt, pepper, and ginger powder. Mix well until all ingredients are fully incorporated.
Form the mixture into meatballs, about 1 inch in diameter. Place the meatballs in a single layer in the slow cooker.
In a separate bowl, mix the teriyaki sauce and pineapple chunks. Pour this mixture over the meatballs in the slow cooker.
Cover and cook on low for 4-6 hours or on high for 2-3 hours, until the meatballs are cooked through.
If desired, sprinkle sesame seeds over the meatballs before serving.