Preheat an oven to 400 degrees F. Rub the skins of the potatoes with about 2 tablespoons of oil and season with salt and pepper. Arrange the potatoes on a baking sheet and bake until tender, about 1 hour. Remove the baked potatoes from the oven and let rest until cool enough to handle, about 10 minutes. While the potatoes are baking, place a heavy-bottom pot over medium-high heat with the remaining 2 tablespoons of oil. Reserve a few tablespoons of chopped onion to garnish the finished potatoes and add the remaining to the pot along with the garlic. Cook, stirring occasionally, until tender, about 5 minutes. Add the ground beef and chili powder to the pot and continue cooking until the meat is browned, 8 to 10 minutes. Add the tomato sauce, kidney beans, Worcestershire and 1 cup of water to the pot and bring the liquids up to a simmer. Reduce the heat to medium-low, season with salt and pepper, and simmer the chili until thickened, about 15 minutes. Reserve warm.
When the potatoes are cool enough to handle, carefully scoop the flesh out into a large mixing bowl, taking care to keep the skins whole and intact. Ladle about 2 cups of the prepared chili into the bowl with the potatoes and mash them to combine. Scoop the loaded filling back into the potato skins. Garnish the potatoes with the cheese, chips and reserved onions. Serve warm.