Preheat oven to 180 degrees C. Grease a deep souffle dish.
With an electric mixer, beat butter, sugar, egg yolks and lime zest until light and fluffy. Alternately fold in the flour and milk to make a smooth batter. Stir in lime juice.
In a separate bowl, whisk egg whites until firm. Gently fold egg whites into batter. Pour batter into souffle dish.
Place dish in a baking tin and fill tin with enough boiling water to come 1/3 of the way up the dish. Gently transfer to oven and bake 50 minutes, or until top is golden. Dust with icing sugar and serve with cream.