Drain the soaked beans and put them in a pot with the bay leaf and fresh cold water to cover by an inch or so.
Bring to a boil, decrease heat to keep the liquid simmering steadily, and cook, partially covered, about 40 minutes, or until the beans are cooked through but not mushy.
Turn off the heat, stir in 1/2 teaspoon salt, and let the beans cool for a while in the pot, absorbing some of the cooking liquid.
To make the soup: peel and core the apples, and cut them into 1/4-inch-thick slices.
Put 4 tablespoons of the butter in a heavy saucepan, and set it over medium heat.
As soon as the butter melts, scatter the apple slices in the bottom and drop in the cloves.
Cook the apples for 3 minutes, or until they begin to soften, turning and stirring them gently.
Drain the cooked beans, and add them to the pan, then pour in the hot water--all 8 cups if you are making soup; 6 cups to make a side dish with thicker consistency.
Increase the heat, and stir in the lemon zest, cinnamon, and remaining 1 1/2 teaspoons salt.
Cover the pan, bring the liquid to a boil, then set the cover ajar and lower the heat to keep the soup bubbling gently; simmer 10-15 minutes, until the apples are completely soft and the liquid has the consistency you like for soup.
Turn off the heat, stir in the remaining 2 tablespoons butter, and serve.