Preheat oven to 275°F. Line a rimmed baking sheet with parchment paper.
In a medium saucepan, melt the butter over medium heat. Cook, stirring often, until the butter foams, then browns (but do not let it burn), about 5-8 minutes. Remove the butter from the heat and transfer it to a bowl. Whisk in the brown sugar, maple syrup, orange zest, and vanilla extract. Set aside.
In a food processor, pulse the pecans until they are almost a powder (but with a few larger pieces remaining).
In a large bowl, combine the pecans, oats, almonds, pumpkin seeds, sunflower seeds, flax seeds, chia seeds, cinnamon, cardamom, nutmeg, and salt.
Drizzle the reserved butter mixture over the oat mixture and toss to combine.
Spread the granola out onto the prepared baking sheet and bake, tossing occasionally, until golden brown, about 40-50 minutes (the mixture will still look wet, but it will dry as it cools).
Allow the granola to cool completely on the baking sheet.
Mix in the chopped dates.
Store the granola in an airtight container at room temperature. This recipe yields about 5 cups of granola. Enjoy!