Preheat the oven to 120 Celsius (250 Fahrenheit) and place the oats, nuts, seeds, salt flakes and cinnamon in a bowl. Toss to combine. Add the maple syrup and coconut oil and toss to combine, making sure everything is evenly coated.
Spread the mixture out on a tray lined with baking paper and bake for 1 hour, stirring every 30 minutes or so to ensure the mixture browns evenly. When golden leave to cool. Add the cranberries, if using, and store in air tight jars.