No no no no no no no.
I am a s'mores EXPERT.
First of all you need proper graham crackers. None of this digestives malarkey.
Take two large marshmallows and 6 to 8 squares of good milk chocolate, sandwich between two graham crackers and wrap in tin foil. Place in campfire on some nice coals. Fish out carefully after about 5 mins with a big stick. Unwrap without (a) burning your fingers or (b) getting ash in the s'more. Enjoy.
N.B. recipe tastes best if prepared on canoe trip in Canada.