Vanilla Ice makes the perfect amount to fill this tray
1 cup milk
1 vanilla bean, split lengthwise
2 tablespoons sugar (optional)
Combine milk, vanilla bean, and sugar (if using) in a small saucepan over low-medium heat and bring to a simmer, simmer for about 10 minutes, stirring occasionally. Remove from heat and let cool completely. Discard the vanilla bean and pour into ice cube molds, then freeze.