Preheat the oven to 180°C (fan). Line a 20cm square tin with parchment paper.
Spread the oats and bran on a baking tray and toast in the oven for 12-14 minutes, stirring once. You're looking for a gentle golden hue and that telltale toasted aroma – this step is crucial for developing flavour.
Toast the mixed seeds and chopped almonds separately until lightly golden and fragrant. Set aside to cool.
Now place the chopped apple in a small saucepan with 4 tablespoons of water. Partially cover with a lid and simmer gently until completely soft and yielding – about 5-8 minutes.
Add the softened apple to a blender with the pitted dates. Blitz until smooth, adding a splash of extra water if needed to coax the mixture into a purée. Transfer to a medium bowl.
Place the almond butter and maple syrup in a small saucepan. Warm gently over low heat, stirring until the mixture becomes fluid and completely combined – this shouldn't take more than a minute or two.
Add this glossy mixture to the date and apple purée and stir until incorporated.
In a large bowl, mix together all the toasted oats, bran, seeds, almonds, cacao nibs, desiccated coconut, and a generous pinch of Maldon salt. Pour in the wet mixture and stir thoroughly until every oat and nut is evenly coated in that sticky,
Tip the mixture into your prepared tin. Press down firmly and evenly, working the mixture into all the corners – the base of a glass or small mug makes an excellent tool for achieving a compact, even layer.
Cover and refrigerate for at least 2–3 hours, or until completely firm.
Remove from the tin, and cut into bars or squares of your preferred size. A sharp knife, cleaned between cuts, will give you the neatest edges. Store in a lidded container for up to 7 days at room temperature, 10 days if refrigerated.