Fresh rosemary infuses lightly sweetened apples with an unexpected aroma and flavor.
Preheat oven to 450, with rack in top position. Bring cider and rosemary to a boil. Remove from heat, and let stand for 5 minutes. Discard rosemary.
Combine sugar, cinnamon, and salt in a large bowl. Add apples, and toss. Coat a nonstick rimmed baking sheet with cooking spray. Arrange apples in a single layer on sheet. Bake for 9 minutes, then flip each slice, and bake for 5 minutes more. Pull out baking sheet on oven rack, and carefully pour infused cider over apples. Return sheet and rack to oven, and bake until apples are soft and glossy, about 5 minutes.
Broil apples with oven door slightly ajar, rotating sheet halfway through, until edges are golden, about 2 minutes. Divide apples and juices among bowls. Serve with yogurt, if desired.