1. Preheat the oven to 250°F. Line two large-rimmed cookie sheets with parchment paper. Spray with baking cooking spray.
2. In a very large bowl, combine the dry ingredients - oats, coconut, and nuts. Mix well.
3. In a separate bowl, whisk together the oil, salt, maple syrup, peanut butter, and vanilla.
4. Pour the wet ingredients over the dry mixture in the bowl, stirring and tossing until everything is very well combined.
5. Spread the granola on the baking sheets, patting it gently to flatten.
6. Bake the granola for about 90 minutes, stirring the mixture with a heatproof spatula every 15 minutes or so. You want to bring the granola at the edge in towards the middle, so it all browns evenly. Reverse the baking sheets in the oven (top to bottom, bottom to top) each time you stir.
7. When the granola is a medium golden brown, remove it from the oven and cool completely on the pans.
8. Store the granola in a tightly closed container at room temperature for several weeks; freeze for extended storage. Or makes great gifts in plastic baggies!
Adapted from King Arthur Flour.