Preheat the oven to 160C/325F/Gas 3.
Sprinkle the oats, linseeds and bran onto a baking tray. Drizzle over the maple syrup and roll the dry ingredients around on the baking tray to coat them in the syrup.
Bake the syrup-coated ingredients in the oven for 15-20 minutes, shaking the tray a few times as the contents cook. Remove from the oven when golden-brown and set aside to cool.
When the oat mixture has cooled to room temperature, tip it into a large airtight container and stir in the nuts, dates, goji berries, hemp seeds and cinnamon until well combined.
To serve, scoop a handful of the granola into a cup of Greek-style yoghurt and top with grapes, melon and chopped mint. Alternatively, eat as cereal with milk.