In a saucepan, melt butter. Slightly cool and pour into a mixing bowl. Add sugar, vanilla, eggs, and dry ingredients. Mix until incorporated. Add chocolate chips and stir.Press half of the cookie dough into a large oven safe skillet pan. Break graham crackers in half and place over the dough. Break the chocolate bars into pieces and add them and the halves marshmallows to the skillet as well. Use a small cookie scoop or a spoon to add the rest of the dough to the skillet. Use a spoon to spread out the dough slightly.Bake in a 350 degree oven for 30 minutes. The center will not be set when you remove it from the oven. Cool slightly and top with ice cream if desired.