Adjust an oven rack to the middle position and heat the oven to 450 degrees. Toss the squash and onions with oil, salt, and pepper on a rimmed baking sheet until evenly coated.

Roast the squash mixture until the vegetables are tender and the edges have started to char, about 25 to 30 minutes, stirring halfway through.

Transfer 2 cups of the roasted vegetables to a blender. Add the peanuts and water; blend on high until completely smooth, which provides the rich backbone for the stew.

Heat the remaining oil in a large pot or Dutch oven over medium-high heat until it shimmers. Add the bell pepper and jalapeño and cook until the peppers have softened and the edges are slightly browned.

Stir in the garlic, ginger, cinnamon, coriander, and cayenne. Cook until the spices are fragrant and the garlic has softened, about 1 minute—this blooming phase is essential for unlocking the spice oils.

Add the diced tomatoes with their juice, coconut milk, water, and quinoa. Bring the mixture to a simmer, then reduce the heat to medium-low and cook until the quinoa is tender and the white 'tails' have spiraled out.

Stir the peanut-squash puree and the remaining roasted vegetables into the pot. Simmer for a few minutes more to meld the flavors together and thicken the broth.

Stir in the cilantro and season with additional salt and pepper to taste. Serve hot, perhaps with a dash of your favorite hot sauce for extra kick.