To make labne, line a medium sieve with muslin or a clean loosely-woven cotton cloth; place sieve over a large bowl. Spoon yoghurt into muslin, cover bowl and sieve with plastic wrap; refrigerate overnight.

Make amaranth pastry: process flour, starch, salt and oil until combined. With the motor operating, gradually add the iced water in a thin steady stream until a dough forms. Flatten pastry into a disc, wrap in plastic wrap; refrigerate 30 minutes.

Grease an 11cm x 34cm rectangular loose-based fluted tart pan. Roll pastry between sheets of baking paper until 3mm thick. Lift pastry into pan, press into base and sides; trim excess pastry. Prick base all over with a fork. Cover, refrigerate 30 minutes.

Preheat oven to 200°C.

Place tart pan on an oven tray; line with baking paper, fill with dried beans or rice. Bake about 15 minutes. Remove paper and beans; bake a further 5 minutes or until browned lightly. Cool.

Reduce oven to 140°C.

Drain labne; whisk in a large bowl with eggs, honey, extract and rosemary. Spoon into cooled pastry case. Bake for 25 minutes or until just set. Cool to room temperature. Refrigerate until cold.

Meanwhile, place juice and extra rosemary in a medium saucepan; bring to the boil over medium heat. Add orange to pan, reduce heat to low; simmer for 15 minutes or until tender; cool. Just before serving, drain orange slices and arrange over cooled tart.