4 ripe medium peaches (about 1 1/2 pounds), pitted, cut into 1/2″ cubes
1 tablespoon dark brown sugar
1 teaspoon ground cinnamon
1 cup whole milk
1/4 cup granulated sugar
1/8 teaspoon kosher salt
1/2 vanilla bean, split lengthwise, or 1/2 teaspoon vanilla extract
3/4 cup crema (Mexican salted cream) or sour cream
3 tablespoons powdered sugar
1 teaspoon fresh lemon juice
Preheat oven to 400°F. Toss peaches with brown sugar and cinnamon on a parchment-lined rimmed baking sheet. Roast until peaches release some juices but are still holding their shape, 10–15 minutes. Let cool.
Meanwhile, combine milk, granulated sugar, and salt in a medium saucepan. If using vanilla bean, scrape in seeds and add pod (wait if using vanilla extract). Cook over medium heat, stirring occasionally, until sugar is dissolved and mixture comes to a gentle boil, taking care not to scald, about 5 minutes.
Remove from heat, then transfer milk mixture to a medium bowl. Add crema, powdered sugar, and lemon juice and whisk until smooth. Whisk in vanilla extract, if using. Let cool slightly, then discard vanilla bean pod, if needed, and chill until cold.
Fill each ice-pop mold with crema mixture to a height of 1″. Freeze until mixture begins to set, about 30 minutes. Divide peaches among molds, then evenly pour remaining crema mixture into each mold, leaving at least 1/2″ from top of mold.
Place lids over ice-pop molds, insert sticks, and freeze until ice pops are solid, at least 4 hours.
Just before serving, dip molds briefly into hot water to release.