Preheat oven to 300 degrees Fahrenheit. Line a sheet pan with parchment paper or a silicone baking mat.
In a food processor, add ¾ cup of oats and pulse until finely ground but before it reaches a flour consistency
In a large bowl, combine the ground oats, remaining old fashioned oats, cinnamon, golden flax meal, kosher salt, and chopped walnuts. Stir to combine.
In a heatproof bowl, melt the coconut oil in the microwave. Add the maple syrup and vanilla. Stir, then pour over the oat mixture
Use a large spoon to stir the mixture until it’s evenly coated with the syrup mixture. Transfer the granola to the prepared pan in an even layer about ½ inch thick. It won’t fill up the entire pan. It’s important the granola is touching (not spread out too thin) to make clusters at the end
Bake for 20 minutes, then rotate the pan. Bake for 25 more minutes
Remove the sheet pan from the oven and let the granola cool for at least 30 minutes before you break it into pieces.
Once it’s broken into clusters, let it cool completely before transferring it to a zip-top bag