Preheat your oven to 375F
Mix together oats, walnuts seeds, pumpkin spice and salt.
Add the pureé, maple syrup, olive oil and vanilla and mix well.
Spread out on a parchment lined baking sheet and form it into a big square, about 1 centimeter thick
Bake at 375F for 25-30 minutes or until the edges are golden brown.
Let it cool completely and then crunch into big chunks.
Store in the pantry for 1-2 days or in the fridge for up to 5 days.