Combine the zest with sugar, add juice, mix well, add yolks mixed with a fork and leave for 30 minutes. Strain, cook in a saucepan for 7-9 minutes, stirring constantly. When the mixture begins to thicken, remove from heat, add butter, let cool.
Whip the whites, gradually adding the powdered sugar. Spoon swirls around the edges to form a shallow bowl shape. Bake at 110 °C (230 °F) for an hour, at 60 °C (140 °F) for 3 hours, the convection mode is prefered
Whisk the cream, fill Pavlova and decorate with curd and kumquat.