1.Preheat oven to moderate, 180°C (160°C fan-forced). Grease a 20 x 30cm lamington pan and line with baking paper.
2.Heat honey and one-quarter of butter in a small saucepan, stirring until smooth. Transfer to a medium bowl; stir in raisins, pepitas, oats, coconut and apricots.
3.Beat sugar, egg yolk and remaining butter in a small bowl with an electric mixer until light and fluffy.
4.Mix in sifted flour and custard powder. Press mixture over base of pan; sprinkle with muesli. Bake about 25 minutes.