I love s'mores, I think it is my favourite flavour combination. I found this awesome recipe from The Happy Baker. It's the best recipe for s'more squares out there, even better than Martha Stewart's. I give these squares as presents as everyone loves them and they go great with hot chocolate. Here is the recipe with a couple tweaks.
2/3 cup sugar
1/2 cup butter softened
1/2 tsp vanilla
2 and1/3 cups graham crumbs
1/3 cup flour
1/2 tsp salt
1, 7 oz. container of fluff
2 cups semi-sweet chocolate chips
1 1/2 cups mini marshmallows
Incorporate the first seven ingredients in a bowl with a whisk or with a hand held blender. Reserve 1 cup of the mixture and press the rest into the bottom of a 9 x 13 baking pan. Put the fluff into the microwave for about 30 seconds and spread the fluff over the graham mixture. Sprinkle chocolate chips all over the fluff and then the marshmallows over the chocolate chips. Sprinkle the remaining graham mixture on top and press into the marshmallows.
Bake for 20 - 25 minutes in a 350 degree oven. Let sit and cut into squares.