1.Preheat oven to 180°C/160°C fan-forced. Grease 20cm x 30cm lamington pan; line base with baking paper.
2.Make macaroon topping.
3.Beat butter, rind, sugar and egg yolks in medium bowl with electric mixer until light and fluffy. Stir in flour and milk, in two batches. Spread mixture into pan; spread with topping.
4.Bake cake about 30 minutes. Stand cake in pan 5 minutes; turn, top-side up, onto wire rack to cool. macaroon topping Beat egg whites in small bowl with electric mixer until soft peaks form; gradually add sugar, beating until dissolved. Stir in extract and coconut.