Preheat oven to 400F. Line 2 large baking sheet pans with aluminum foil and set aside.
In a small frying pan combine the whole coriander and whole cumin seed. Heat the pan over medium high heat. Stir occasionally while heating to toast the seeds. It will take about 5 minutes and the spices will be more aromatic. Remove from heat and let cool slightly. Then put the toasted spices in the grinder attachment along with the chili powder, ground cinnamon, and ground nutmeg. Pulse until the seeds are ground. Set aside.
In a large bowl combine the butternut squash, onions, chickpeas and olive oil. Toss to coat.
Add the spice mix to the vegetables and mix together until all the vegetables are evenly coated.
Evenly distribute the vegetables onto the two prepared baking sheet pans. Roast in the oven for 45 minutes. Set aside.
In a large pot over medium-high heat, melt the butter and continue to cook it until it starts to brown. Add the garlic and sauté for 30 seconds.
Add the roasted vegetables and stir to thoroughly mix with the garlic. Add the vegetable stock and almond butter.
Working in batches, add to a blender and puree until smooth. You will need to have a separate bowl to pour the blended bisque into. Once you have blended all the vegetables, add them back to the pot.
Cover the pot and put it back on the stove over medium high heat. Cook for about 5 more minutes.
Serve with roasted pepitas (pumpkin seeds) and sour cream.