In a saucepan mix together water and sugar. Bring to a boil over medium-low heat. Simmer until sugar is completely dissolved. Add the orange rounds and cook them for 20 minutes, util tender. Cool and drain the syrup. Reserve the syrup and 6-7 orange slices, you will need them later. Preheat oven to 180 F. Grease the baking dish with the butter. Arrange the orange slices on the bottom and the sides of the baking pan. In a food processor pure reserved oranges and 1/4 sup of syrup. In a medium-sized bowl whisk together flour, baking powder almond meal and poppy seeds. In a different bowl beat the eggs and sugar until pale. Add the orange puree and flour mixture, mix carefully. Pour cake batter evenly over the orange slices in your baking dish. Bake for 40-45 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow cake to cool in the pan. Then place serving plate over the baking dish and carefully invert the cake. Keep the dish on the plate until the cake falls into the plate. Serve with vanilla ice cream.