Sift the flour into a bowl. Knead quickly with sugar, flaky butter and an egg to form a smooth dough. Roll out on a floured work surface and place in a greased dish. Prick the dough several times with a fork. Pre-bake on the middle shelf for 12 minutes.
For the topping, wash the oranges with hot water, pat dry and rub the peel thinly. Squeeze the oranges and the lime. Mix the juice with the jam and the orange peel. Beat the remaining eggs, powdered sugar and custard powder until frothy. Gradually stir in the orange mixture. Whip the cream until stiff and fold in. Pour the orange cream on the batter. Bake in the oven at 150 ° C (center, fan 130 ° C) for about 40 minutes until the cream is firm. Let cool completely in the tin, then dust with icing sugar.