Preheat the oven to 90°C (200°F/Gas ½). Cut the mango into slices about 5 mm (¼ inch) thick and lay them flat on a baking tray lined with baking paper, making sure they don’t overlap or touch. Place in the oven for about 45 minutes. Turn them over, then continue baking for a further 45 minutes. Allow them to cool and then lay them flat in an airtight container between layers of baking paper so they don’t stick together.
Preheat the oven to 150°C (300°F/Gas 2). Combine all the dry ingredients in a bowl. In a large saucepan, heat the coconut oil, sugar, honey and vanilla over medium heat, whisking constantly. Remove from the heat when the mixture starts to boil. Immediately pour over the dry ingredients and mix together carefully with a spatula. When the mixture is evenly coated, pour it onto a baking tray lined with baking paper and spread out into a layer about 1.5 cm (⅝ inch) thick.
Cooking and Serving
Bake for about 40 minutes, checking its progress at regular intervals. If the granola is browning too quickly, reduce the oven temperature to 140°C (275°F/Gas 1) and cover the granola with a sheet of foil. When it starts to dry out and form clumps, remove the tray from the oven and stir gently with a spatula. Return to the oven for 20–30 minutes. Cut up the mango slices if you need to and mix them into the granola, then return to the oven for 10 minutes. Allow to cool at room temperature before breaking the granola into pieces. The granola will keep for at least 3 weeks in an airtight container at room temperature.