6 cups (1-inch) seedless watermelon cubes (2 pounds; from 1/2 personal seedless watermelon)
1 cup sweetened condensed milk
1/4 teaspoon kosher salt
Arrange the watermelon in a single layer on a parchment paper-lined baking sheet. Freeze until solid, about 4 hours.
Combine the frozen watermelon, sweetened condensed milk, and salt in a food processor and blend until smooth, 3 to 5 minutes. Move the soft sherbet to an airtight container and freeze until solid, approximately 2 hours.
- Make ahead: Watermelon cubes can be frozen up to 1 month in advance. Just store in a freezer zip-top bag until ready to use.
- Storage: This sherbet will keep well in the freezer for up to 2 weeks.