Preheat your oven to 325°F.
First combine the oats, wheat bran, nuts, and seeds in a bowl and mix together.
Add in the diced apple and mix again until well combined.
In a smaller bowl, whisk together the maple syrup, oil, brown sugar, cinnamon, vanilla, and salt until well combined.
Pour the wet ingredients into the dry mixture and use a spatula to thoroughly combine.
Transfer the mixture to a lined baking sheet and spread into an even layer.
Bake for 30-40 minutes, gently tossing every 10 minutes. Allow to cool for 30 minutes before transferring to an airtight jar or ziploc bag for storage.