6 Granny Smith apples
Core, peel, and slice the apples. In a large frying pan or Dutch oven, melt 4 tablespoons of the butter and add the apple slices. Over medium-low heat, cook and stir the apples until they begin to soften, about 5 to 10 minutes. Remove them to a bowl. Melt the remaining butter in the pan and add the brown sugar. Over medium-low heat, stir until the sugar dissolves.
Remove the pan from the heat. Add the cognac to the butter mixture, stir it in, and heat this mixture over medium heat until it begins to boil. Boil for 4 minutes, stirring constantly.
Return the apples to the pan, place the pan over medium heat, and stir occasionally until the apples are hot. Either serve immediately or cool and briefly reheat at serving time.