Preheat the oven to 325ºF. Line a large rimmed baking sheet with parchment paper.
Pour the almonds, cashews, pecans and pumpkin seeds onto the pan and set it aside.
In a small bowl, combine the rosemary, maple syrup, melted butter, salt, vanilla, and chili powder. Gently whisk until blended.
Pour the mixture over the nuts on the prepared baking sheet. Stir well, until all of the nuts are lightly coated. Spread the mixture in a single layer across the pan.
Bake, stirring after the first 10 minutes and then every 5 minutes thereafter until almost no maple syrup remains on the parchment paper and the nuts are deeply golden for about 25 minutes.
Remove the pan from the oven and stir the nuts one more time, spreading them into an even layer across the pan. Let them cool down for about 10 minutes, then, while the nuts are still warm, carefully separate any large clumps.
Let the nut mixture cool completely on the pan. Taste for seasoning. Store in airtight container at room temperature. Enjoy!
