Preheat the oven to 200 degrees C. Whisk the peach nectar with 1/3 cup sugar, 1 tablespoon flour and half the nutmeg in a medium saucepan. Cook over medium heat, whisking constantly, until the mixture starts to thicken. Cook and whisk for 2 minutes more, or until thickened. Stir in the peaches and lemon rind and cook until bubbly. Keep warm.
Combine 2/3 cup flour in a medium bowl with the rolled oats, 2 tablespoons sugar, the baking powder and the remaining nutmeg. Using a pastry blender or two knives, cut in the butter until the oat mixture resembles coarse breadcrumbs.
Combine the milk and egg in a small bowl. Add them to the oat mixture and stir until a dough forms.
Spoon the warm peach mixture into a round 23 cm cake tin. Spoon the dough into four even mounds on top. Bake for 18–22 minutes, or until a toothpick inserted into the centre of a mound of dough comes out clean.
Serve the cobbler warm, accompanied by cream or ice cream.