Step 1
Preheat the oven to 350 degrees F (175 degrees C).
Step 2
Mix together graham cracker crumbs melted butter sugar and salt for the crust and press into the bottom of a springform pan.
Step 3
Mix graham cracker crumbs condensed milk chocolate chips baking powder and salt for the graham brownie in a large bowl until well combined. Gently spread on top of graham cracker crust.
Step 4
Bake in the preheated oven until top is dry about 30 minutes. Remove pie from the oven and set aside to cool slightly. Increase oven temperature to 425 degrees F (220 degrees C).
Step 5
Meanwhile whisk together sugar cocoa powder cornstarch and salt for the chocolate custard in a saucepan. Gradually whisk in milk. Cook and stir over medium-high heat until thickened 5 to 7 minutes. Reduce heat to medium-low and cook for about 2 minutes more. Pour beaten egg gradually into the chocolate custard stirring as you pour. Cook and stir for 2 minutes. Remove from the heat and stir in vanilla extract.
Step 6
Pour chocolate custard over the baked pie. Arrange regular marshmallows on top of the pie and sprinkle miniature marshmallows to fill in any gaps.
Step 7
Bake until marshmallows are lightly browned about 5 minutes; keep an eye on it because you do not want marshmallows to melt.
Step 8
Place cream for chocolate ganache in a microwave-safe bowl. Microwave on High until hot making sure it doesn't bubble over about 45 seconds to 1 minute. Mix in chocolate butter and coffee granules. Microwave for another 30 seconds then stir until smooth. Let sit until it thickens 15 to 20 minutes. Drizzle chocolate ganache over the pie.