Peel and slice the apples, then place them in a slow cooker (4 quart or larger). Add the lemon juice, brown sugar, cinnamon, cloves, vanilla, salt, and cornstarch to the slow cooker, then stir to coat the apples in the spices.
Divide the butter into pieces, then place the butter on top of the seasoned apples. Pour 1/2 cup water into the cooker down the side so that reaches the bottom without rinsing the spices from the apples.
Place the lid on the slow cooker, set it to high heat, and cook for two hours. After two hours, stir the apples well, replace the lid, and cook for an additional one hour, then serve hot.