Preheat the oven to 350 degrees (177 C) and line a baking sheet with parchment paper.
Mix the oats, walnuts, pumpkin seeds, ground flax seed, pumpkin pie spice, and cinnamon together in a large bowl. Stir well to mix.
In a pot, combine the maple syrup, brewed coffee, and pureed pumpkin. Place over medium-low heat and whisk until all ingredients are well distributed and it is warmed through (about 4 to 6 minutes). Pour it over the dry ingredients and mix with a spatula. Spread across the baking sheet and bake for 25 to 30 minutes, or until golden brown. Rotate the pan at the halfway point. (note: Don't stir as this will break up the clusters).
Remove the granola from the oven and let cool completely. It may seem wet, but it will crisp up as it cools.
Divide into bowls or store sealed in a jar until ready to use. Enjoy!