Heat oven to 350. Cut the top 1/2 inch off the top of each apple. Using an apple corer or melon baller, scoop out stem, core and seeds, leaving apple in tact. Stand in a 9in. baking dish, cut side up.
Divide 1/4 cup of each candy bar pieces among apples, about 2 tablespoons in each. On top of that, place about 1 teaspoon or so of butter on each apple/top of candy bar pieces. Divide remainder of candy bar pieces among apples and sprinkle on top of butter.
In a small bowl, whisk together cider and sugar. Pour over apples. Carefully place baking dish in oven and bake for about 1hr 15mins. Check at about 45 mins. you don't want to over bake your apples or they get mealy. When apples are tender and done, remove from oven and let set for 5 mins. before serving. Top with vanilla ice cream or whipped cream if desired.