First, set a layer of cake right side up on your turntable. Then, place on top of that one of the discs of graham cracker crust. It's okay if it breaks, just get it in the center of the cake layer as best as you can.
Fill your piping bag with some buttercream. You don't need a tip on the bag right now. Pipe a large "dam" of buttercream around the outside of the graham cracker crust. Make sure that the "dam" is higher than the graham cracker crust to ensure the ganache does not leak out.
Pour in some ganache over the top of the graham cracker layer. It should settle nicely into the buttercream "dam" you created.
Place a small amount of buttercream over the top of the ganache to seal it in. It doesn't have to look perfect, just make sure no ganache is leaking out.
Repeat this process again, starting with the cake layer, then the graham cracker crust, buttercream dam, ganache, and more buttercream.
Flip the final cake layer over so that the smooth pan side is facing up. This helps create nice, smooth cake edges. Place it on top of your cake.
Using the buttercream piping bag, lay down a layer of buttercream on top and on the sides of your cake. This will form your crumb-coat, so it in no way has to look good at first. Just get the buttercream on there.
Use your cake scraper to smooth the buttercream around the top and outside of your cake. Add more buttercream where needed, and smooth again. It's okay if you get a smooth finish but see the cake through it - in fact, you should at this point.
Place the cake in the freezer for 15 minutes or the refrigerator for 30 to let the crumb coat chill.
Once the crumb-coat has hardened a bit, apply a second layer of buttercream. Use the bench scraper again to smooth out all of the imperfections. Apply more buttercream with an offset spatula where there are holes, and, yes, keeping smoothing. When finished, let chill in the same manner as before.
Cut out a thin strip of parchment paper to act as a guide for your graham cracker crumb garnish. Press this gently into the buttercream where you don't want graham cracker crumbs.
Crush the leftover, roasted crumbs into a fine dust, and, using your forefingers, press a small handful onto the bottom of your cake. Once the cake is covered to your liking, remove the parchment paper guide and discard it.
Chill your cake before applying the ganache drip, as you chilled it previously. Test the ganache for proper consistency by using a piping bag or spoon to drip it down the side of the bowl. Cool it to thicken, or heat it to loosen, as needed. Once the drip consistency is to your liking, carefully apply it to the cake, starting on the back until you get the hang of it. Use the excess ganache to cover the top of the cake, smoothing it to your preference.
Prepare your piping bags with the tips of your choosing, and add meringue into them. Using a circular motion or a drop-flower motion, add some swirls and garnishes where you see fit. I like to start on the top with some big, dramatic rosettes, and slowly cascade smaller ones down the sides. Feel free to get creative with it.
Finally, turn on your kitchen torch according to the instructions. Gently at first, hold the flame towards the meringue. It will heat quickly, as you'll see, so with sweeping motions, toast evenly around the meringue. If any catch fire, simply blow on them to burn it out. After all, it's just like making s'mores.