If making the s'mores indoors, then select the broil button on the oven.
Place a sheet of parchment paper or a cookie sheet on a baking tray.
Layer the s'mores together. Start with one graham cracker as the base, top with one of the chocolate pieces, then a marshmallow, and the second graham cracker on top. Repeat to make 10 s'mores.
Once the oven is ready, place the baking tray in there for 1-2 minutes. The s'mores will begin to burn quickly, so keep a close eye on them. Remove the tray from the oven as soon as the marshmallows begin to get toasted. Each oven will vary, but my oven took a full 2 minutes.
Once the baking tray is removed from the oven, enjoy the s'mores while they're hot!
Outdoor Method
If making the s'mores outdoors over a campfire, then put one marshmallow on one skewer or stick at a time. Toast the marshmallows over the campfire until golden brown.
Place each marshmallow with a square of chocolate in between two graham crackers, to form a sandwich.
Enjoy warm!
Notes
Storage
I do not recommend to store these, as the marshmallows won't have the same texture as when they're freshly toasted.