Preheat the oven to 400°F then line a baking sheet with parchment paper. Cut the stem off of the butternut squash then slice down the center lengthwise. Using a spoon, scoop out the seeds and any strings of flesh. Lightly grease the flesh with high heat oil then lay facing down on the baking sheet. Roast for about 45 minutes, until soft when squeezed with an oven mitt. Reduce heat to 350°F and set squash aside to cool.Meanwhile, warm a large skillet with one tablespoon extra virgin olive oil. Add the onion and cook for 3 minutes, until translucent. Then add the jalapeño and garlic, and continue to cook for 2 more minutes.To the skillet, add the brussels sprouts along with the spices and salt. Cook for about 5 minutes, until brussels begin to soften. Add the black beans and stir to combine. Remove from heat and set aside.Once the squash has cooled, use a spoon to scrape out the flesh into a large bowl. Transfer the vegetable mixture from the skillet to the bowl. Stir together to combine.Place the tortillas on a microwave safe plate and cover with a lightly damp paper towel or tea towel. Microwave for about 20 seconds to soften. This step will help the tortillas be more pliable for rolling.Spread about 1/2 cup of the salsa on the bottom of a 9 x 13 baking dish. Add about 1/3 cup of the filling inside of each tortilla. Roll up then place in the baking dish seam side down until you have assembled all 12 enchiladas. Spread the remaining salsa on top then bake in the preheated oven for 25 to 30 minutes.Meanwhile prepare the cashew sour cream by combining all of the ingredients in a high speed blender or NutriBullet. Blend until smooth. Add more water if needed to thin, one teaspoon at a time. Or more salt/lemon juice, if desired.Remove enchiladas from the oven and allow to cool for 5 minutes before serving. Serve warm drizzled with cashew sour cream, cilantro, and pumpkin seeds, and enjoy!