Preheat the oven to gas 4, 180°C, fan 160°C and lightly grease a 20cm (8inch) square tin with a little of the butter.
In a pan or microwave, gently melt the golden syrup with the butter and sugar. Put this in a large bowl and mix in the muesli and apple thoroughly. Tip the mixture into the prepared tin and spread it evenly, pressing down quite firmly with the wettled back of a spoon.
Bake in the preheated oven for 20-25 minutes until the top is crispy and golden.
Leave in the tin to cool slightly. While still warm, cut into squares with a sharp knife. Let cool completely in the tin. Eat within 2 days. Store in an airtight tin lined with kitchen roll.
*Inspired by Lynne T. featured in the Realfood Cookbook
**These flapjacks are very rich and indulgent, so it shouldn't be eaten too often. But they're perfect for those special occasions.
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