Preheat the oven to 250 degrees Fahrenheit.
Melt the butter and brown sugar in a microwavable bowl by placing in the microwave for 3 minutes on 50% power or by heating over low heat in a small pot on the stove.
Meanwhile, stir together the oats, sunflower seeds, wheat germ, flax seeds, and poppyseeds in a large bowl and set aside.
Once the butter and honey have melted, whisk in the brown sugar, vanilla, nutmeg, and salt. Pour the mixture over the oats, etc. Stir well to combine. Add the egg white and stir it in as well.
Line a rimmed baking sheet with parchment paper. Dump the mixture onto the sheet and spread evenly, making sure to press the mixture into the corners. Bake for 60 minutes in the pre-heated oven, rotating once halfway through. Remove from the oven and allow the granola to cool (without stirring!).
When cooled, break into small pieces. Store in an airtight container.