The original slow cooker recipe is listed below - my notes for multiplying the recipe and converting to cook in an 18-quart Roaster Oven will be listed below that.
8 cups diced apples (peeled and cored)
1 cup dark brown sugar
1 tablespoon ground cinnamon
4 tablespoons unsalted butter
1/2 teaspoon Kosher salt
1 dash freshly grated nutmeg
2 teaspoons pure vanilla extract
Put all the ingredient in a slow cooker and mix thoroughly. Cover and cook on high until apples are tender, about 3 hours. The yummy salted-cinnamon-vanilla-caramel sauce that coats the apples will thicken slightly upon cooling. Cool uncovered for a thicker sauce.
My conversion to feed a crowd of 40: I quadrupled the recipe and cooked it in my 18-quart electric roaster set to 300F for about 2 hours, stirring occasionally. I used a mix of apples - galas, golden delicious, golden supreme, and Nittany. Any apple that keeps it's shape during baking will work well.