The Japanese pumpkin, also called kabocha, is a type of winter squash. Shaped like a pumpkin, the outer rind is green instead of orange, and the yellow pulp has a sweet flavor. Kabocha is harvested and then allowed to ripen over the course of a month or two. It then can be used in tempura, side dishes and soups.
Preheat oven to 350 degrees Fahrenheit.
Cut the kabocha in half. Remove the seeds and attached strings. Use a fork to poke the interior in in 5 to 10 random places. Wipe the inside of each piece with olive oil and set them, face down, in a shallow baking pan. Add 1/2 inch of water to the pan. Bake for 45 minutes. Continue with the rest of the recipe while the kabocha bakes.
Add butter and 2 teaspoons of olive oil to a heavy skillet and heat over medium heat until the butter is melted. Add the onions and cook, stirring occasionally, 30 to 40 minutes or until the onions are caramel colored. Add more oil if the onions begin to stick.
Remove the kabocha from the oven and allow to stand until cool enough to work with. Scoop the flesh out of the skin and place it in a large bowl. Add the onions, coconut milk and broth and stir until smooth. In batches, puree the mixture in the food processor, adding each batch to a large stock pot when finished. Warm the soup over low heat and add salt and pepper to taste. Serves eight.