Spread popcorn on a large baking sheet. Make sure to remove all unpopped kernels. Break graham crackers into small bite size pieces.
Sprinkle 1 cup of chocolate chips, marshmallows, and graham cracker pieces over the top of the popcorn.
Melt remaining 1 cup of chocolate chips in microwave on high power for about 2 minutes, stirring each 30 seconds. If the chocolate has trouble melting, add 1 teaspoon vegetable oil.
Drizzle melted chocolate over the top of the popcorn. Lightly toss to semi-coat. Chill until set.