In a large bowl combine the oats, seeds, nuts, and salt. Stir to distribute everything evenly.
In a small saucepan over medium heat, combine the butter, brown sugar, and cinnamon. Bring to a simmer and let it go for 2–3 minutes, stirring occasionally. Remove from heat and stir in the vanilla.
Drizzle the warm mixture over the dry ingredients and toss gently with a wooden spoon until everything is evenly coated. Take your time here — you want every oat covered.
Spread the granola evenly onto a lined baking sheet in a single layer. Bake at 300°F (150°C) for 20–25 minutes until golden and fragrant. Rotate the pan(s) halfway through if your oven runs uneven.
This is the most important step — let the granola cool completely on the pan before touching it. It crisps up as it cools. Break it apart once fully cooled and store in an airtight jar.