1Preheat the oven to 375 degrees F.
Peel apples. Cut the cheeks from the apple, to remove the core. Cut into fairly thin, but not too thin, slices. Put them in a bowl and add the lemon zest and juice and the orange zest and juice. Toss to coat the apples, then add the molasses, 1/2 teaspoon salt, the cinnamon, ginger, and the nutmeg. Toss to blend.
2Butter the bottom and sides of a shallow pie dish and add apples.
3In another bowl, combine the flour, oats, brown sugar and remaining 3/4 teaspoon salt. Add the butter to the bowl and break it up with your fingers integrating the flour with the butter.
4Top apples with the butter-flour mixture. Put the dish in the center of the oven and bake until the apples are tender when pierced with the tip of a knife. The topping should be golden brown as well, about 35 to 45 minutes.
5Remove from the oven and set aside to cool a few minutes before serving. To serve, garnish with additional lemon zest and ice cream, if desired.