Heat a heavy skillet with a drizzle of oil and a dab of butter. Chop the stems of the chard and start to saute them. Chop or crush the garlic and after about 5 minutes, add them to the pan with the chard leaves, torn or chopped. Cook for a minute, then add the currants and about 1/4 cup of water, cover and cook for a few minutes, until the leaves are tender. Remove the lid and cook the extra moisture off, then stir in the feta and immediately remove from the heat and transfer to a bowl. Serve immediately. Serves 2-4.