Preheat the oven to 400 degrees F. Halve and seed the spaghetti squash; roast, then scrape into strands (see Cook's Note).
Meanwhile, put half of the onion in a small bowl and cover with cold water; set aside. Heat the vegetable oil in a large saucepan over medium heat. Add the remaining onion and the garlic. Cook, stirring occasionally, until slightly softened, about 3 minutes. Add the beef, tomato paste, chili powder, cumin, paprika, cinnamon, oregano, cayenne, 1 teaspoon salt and a few grinds of black pepper. Cook, stirring occasionally, until the beef is browned, about 7 minutes.
Add the tomatoes and 1 1/2 cups water to the beef mixture. Increase the heat to medium high and bring to a boil. Reduce the heat to medium low and simmer, stirring occasionally, until the chili is slightly thickened, about 20 minutes; season with salt and black pepper.
Drain the reserved onion; pat dry. Top each serving of chili with the spaghetti squash, kidney beans, onion, oyster crackers and cheese.
Photograph by Johnny Miller
How to Roast Spaghetti Squash Trim both ends with a chef's knife, then position the squash upright and halve lengthwise. Scoop out the seeds with a spoon and discard. Place the squash halves cut-side down on a baking sheet. Roast at 400 degrees F until tender, 25 minutes; let cool slightly, Scrape the squash into strands with a fork. Discard the skin.
Courtesy of Food Network Magazine