Preheat the oven to 325°F. Line a 13" x 18" rimmed baking sheet with parchment paper.
In a large bowl, stir together the 3 cups old-fashioned rolled oats, 1 cup pumpkin seeds, 1 cup chopped walnuts, 1 ½ teaspoons pumpkin spice blend, and ½ teaspoon fine sea salt. Now pour in the ½ cup pumpkin purée, ½ cup maple syrup, and ½ cup olive oil and stir until well combined.
Spread the granola out on the prepared baking sheet and bake for 30-35 minutes, stirring every 15 minutes. Remove from the oven and let cool completely.
Notes
Use old-fashioned rolled oats. I always use rolled oats when I make granola because they give the granola its hearty texture. Quick oats make a much finer granola that's, well, less granola-y.
Stir or press. Give the granola a good stir halfway through baking so that it browns evenly. For clusters, press the granola down lightly with the back of a wooden spoon after stirring and then let it cool undisturbed so that it sets up a bit.
Keep an eye on the oven. The pumpkin puree adds moisture, so this granola may need a little longer to crisp up than a basic granola. It will also continue to firm as it cools.
Switch up the nuts and seeds. Pecans, almonds, sunflower seeds, or extra pumpkin seeds are all good options here. Just keep the total amount about the same.
Let it cool completely. Make sure the granola is fully cool before transferring it to a jar or airtight container. Storing it while it's still warm can trap moisture and soften the texture.
It may not be as crisp as regular granola. The pumpkin puree holds its own moisture, so note that the granola may soften more quickly than your familiar batch. It's still delicious!
Make it your own. Once the granola has cooled, you can add raisins, dried cranberries, chopped dried apples, or a handful of chocolate chips for extra sweetness and texture (yum!)