Place two cups of milk in a medium saucepan over medium heat. Scrape seeds of vanilla bean into saucepan and add pod in as well. When milk begins to simmer, remove from stove.
Whisk sugar and cornstarch together in a bowl. Add remaining half-cup milk and orange juice and mix well. Add to vanilla milk. Place over medium heat, stirring until thickened, about 10 minutes. Remove from heat and chill overnight.