Line a 9x9 inch pan with parchment paper. DO NOT use an 8x8 inch pan.
Make the ganache: Place chocolate chips in a medium bowl. Place one cup of cream in a microwave safe bowl or large glass measuring cup and microwave it for 60-90 seconds until it is just beginning to bubble around the edges. Pour the cream over the chocolate and place a lid or plate on top of the bowl to catch the steam. Allow the chocolate to sit in the warm cream for about five minutes, during which it will melt. Remove the lid and whisk the cream and chocolate together until smooth and silky.
Place the ganache in the fridge for about 5 minutes while you mix up the cream layer. (Don't leave the ganache in the fridge for longer than 5 minutes or it will set up too hard to spread.)
Make the cream layer: Place the softened cream cheese in a medium-large bowl. Using a hand mixer or stand mixer, beat it well until it is whipped and fluffy. Add the marshmallow creme and beat until incorporated. Then fold in one half of the thawed Cool Whip, then the other half. This completes the cream layer.
Assemble the cake: Cover the bottom of the pan with graham crackers, breaking and trimming to fit it needed. You will use 6.5 crackers. Gently spread 1/4 of the cream across the graham crackers. Then dollop 1/3 of the ganache on top of the cream and gently spread it out.
Repeat the layers two more times: crackers, cream, ganache.
For the final layer, add the remaining graham crackers and the rest of the cream (no ganache should be left at this point). Tightly cover the cake and place it in the fridge for at least 8 hours. This gives the graham crackers time to soften.
To serve, grab the edges of the parchment paper and gently lift the entire cake out of the pan and onto a cutting board. Use a sharp knife to cut cake into slices.
If desired, garnish the cake with chocolate curls or pieces, graham cracker crumbs, and mini marshmallows. You can even toast the marshmallows first using a kitchen torch or the broiler before placing onto the cake.