Preheat the oven to 200 degrees celsius (390 Fahrenheit) and place the cherries, castor sugar and kirsch in a shallow baking dish and toss to combine. Bake for 5 to 6 minutes or until the cherries are cooked but still firm. Set the cherries aside while you make the custard.
To make the custard place the eggs and castor sugar in the bowl of an electric mixer and whisk until frothy. Gradually add the flour and mix to combine. Then add 1 tbs of the cooking juices from the cherries along with the cream, Greek yoghurt and lemon rind.
Brush a shallow baking dish with butter and pour half of the custard over the base of the dish. Spoon the cherries over the custard before topping with the remaining custard. Bake for 25 to 30 minutes, or until the top is golden.