Cut the oat grahams in half, and trim the corners so that you have a round cookie. Set aside.
Place a heat proof bowl over a saucepan filled with water (or use a double boiler). Pour the dark chocolate chunks in the bowl over medium heat.
Stirring constantly, heat the chocolate mixture until it is smooth and melted.
While the chocolate is melting, place the vegan marshmallows into a heat safe bowl. Melt in the microwave for about 20 seconds.
Line a baking sheet with parchment paper. Place a wire rack on top of it. One by one, place a spoonful of melted vegan marshmallow onto a cracker and dip into the melted chocolate. Place on a wire rack over the parchment lined baking sheet or directly on it if you don't have a wire rack.
Place in the fridge to set. Store in the fridge.
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Notes
You can also melt the chocolate in the microwave at 30 second intervals until melted.This recipe will last about 1 week in an airtight container in the fridge.