Preheat the oven to 350 degrees. Spray both sides of the tortillas with cooking spray and carefully drape each tortilla over two bars of the middle oven rack. Cook the tortillas for about 10 minutes or until golden and crispy. Remove them and place on a baking sheet to cool slightly. Turn the oven up to 400 degrees.
While the tortillas are cooking, microwave the chocolate chips and oil in a small bowl at 10 second intervals, until melted.
Divide the mini marshmallows between the taco shells and place the baking sheet with the stuffed tacos back in the oven for about 3 minutes, or until the marshmallows begin to puff and melt slightly.
Optional: using a stick lighter or kitchen blowtorch, char some of the marshmallows to get that campfire flavor!
Remove the tacos from the oven and drizzle with the melted chocolate and garnish with the graham cracker crumbs. Enjoy!!