If using a large Red Kuri, you will have leftover squash that you can use to make a pie or other dish. Alternately, you can save one half of the squash uncooked for use later, but make sure to store it in the fridge and wrap it in plastic.
Soak 1 C. cannellini or other white beans in water overnight. Drain and rinse, then cook in 8 C. salted water with 3 whole cloves of garlic and 2 bay leaves until tender. (You can use canned beans, but you will need to cook the garlic and bay leaves in vegetable broth for at least 1/2 hour).
Cut 1 Red Kuri squash in half, then cook face-down on a baking sheet at 350 degrees. When the cut side is browned and bubbling, remove the squash and let it cool. Scoop out the sides and pulp, then scoop out the orange flesh.
Soak and drain 1/2 lb. spinach leaves.
When the beans are cooked, use a slotted spoon to remove them and the bay leaves from the broth — but not the garlic (you can leave the beans in if you want a completely creamy soup). Add 4 C. of the squash to the broth. Cook it for 5 minutes, then puree in batches. Return the beans to the pot.
Chop the spinach roughly and add to the pot, then turn off the heat. Season to taste with salt, pepper, and lemon juice if needed (to balance the sweetness).