Let stand or microwave for 1 min. until plump. In a large bowl, mix together plumped raisins with liquid and chopped apple slices. Stir in brown sugar. Mixture may be made in advance and refrigerated, covered overnight. In a medium bowl, mix together flour, sugar, baking powder, baking soda, nutmeg and buttermilk until just smooth.
Spoon batter over fruit to cover.
Bake ramekins on a cookie sheet in a preheated oven at 350 degrees for about 30 minutes, until top is brown and bubbly. Serve hot, garnished with mint. Pass the yogurt to spoon over cobbler.