This takes me just under an hour and a half if all goes well (or up to two hours if I have to be careful). Your time will be shorter if you cook both layers at once.
So, you're here, let's begin.
Step 1: Gather Ingredients
Grab your favorite cake mix (2 different flavors) and frosting (complementary to the cake)
Get a half dozen eggs, color doesn't matter - mix them if you like! Just make sure they're fresh...
Oil/butter (I prefer to use sunflower margerine)
Water, and milk.
It doesn't ask for it, does it?
Well, what we're going to do is halve the amount of water and add milk for the rest - trust me, it makes it more fluffy and moist!
Step 2: Gather Tools
Two deep pans (mixing bowls can replace this)
Hand whisk (a mechanical or electric mixer is great if you have one)
Tin foil, saran wrap, toothpicks, and other odds and ends as you see fit.
Like cardboard for a tray!
Step 3: Preparations
All right, so I'm going to assume you know what to put where - just follow the instructions on the box and mix everything from each in a separate pot/bowl.
Butter the pan (I use paper towel to wipe it on), and make sure it's buttered well (idea is at least 1/16" to 1/8" thick, but enough that you can see it).
Once you're ready to go, you ought to have something like the picture below.
At this point, I would preheat the oven.
Step 4: Marbelling... Um... Marballing... Er... Marbling!
I hold one in each hand (it was kinda difficult taking the pictures in between passes, but you get the idea)
Take one flavor and put a thin layer crisscrossing the pan.
Take the next flavor and crisscross over.
An even pattern isn't necessary, but don't make the chunks too thick either - we're looking for variety!
Pass back and forth like this until you've put no more than half the batter in the pan.
Step 5: Into the Oven... for Half the Time?
I put mine in for half the time and then spin the pan and put it back in for the other half of the time.
By doing this you have a better chance of the cake falling (a good thing if you notice it puffing in the middle)
Step 6: Is It Done?
Pull it out of the oven (and close the door to keep the heat in!)
Using a fork or toothpick, poke the center gently and remove - if it comes away clean, you're done.
What does "clean" mean?
Basically, like the picture.
Not clean, to me, is removing the fork/toothpick and it's covered in hot liquid - if this is your case, put it back in for another five minutes.
If you're on your last layer and you've done this once or twice and it's just not cutting it... you can turn the stove off, open the door and leave it sit near the edge (so long as you buttered well enough you won't have to worry about burning it).
Step 7: Removal
Make sure the cake is loose in the pan before flipping it over to get it out - you can loosen it with the rubber spatula by inserting it on the edges and gently nudging it.
Put a plate on the top of the cake, flip the pan and let it fall out
Do not shake the pan! If the cake is stuck, do the spatula thing... if you chunk the cake, you'll need to glue it with frosting (later).
Flip the cake back over (so long as you have a flat pan, the original bottom is guaranteed to be flatter).
Step 8: Oh Noes!
So, you pull the cake out and you have a huge bulge in the middle - fear not, this happens to me all the time... er... I mean it could happen to anyone.
This is what you do - put the cake in the fridge for a little while (30 minutes or overnight if you forget and nobody will snack on it while you're away).
After the cake has stiffened a little (from the cold), take it out and using your large knife cut an even level across the cake.
Put the extra pieces in plastic bags for snacks to share with friends (and entice them to your baking skills)
Step 9: The Tray
A cake tray is wonderful, but if you're frugal then you can make a great tray from an inside out cardboard box (cereal/pizza) wrapped in saran wrap or tin foil (I think tin foil is a better base).
Just fold a large piece of tin foil over a nice piece of cardboard and tape the bottom - keep everything smooth and you'll have a great, inexpensive platter!
Step 10: I Sing, You Sing... No, Wait... Icing!
Place your bottom layer on your presentation piece.
Using the rubber spatula, plaster the top with a thin layer (about 1/4")
Place the top layer centered on the bottom layer, and apply icing to all sides... as evenly as possible.
Well, if you've still got frosting, plaster them smooth (but if it's too obvious maybe you need to use that knife as a trimmer first).
The rubber spatula is your best helper with all of this, but do your best to make it look even.
Step 11: An Odd Way to Travel...
Make a plastic porcupine!
Stick toothpicks at even intervals, and gently place the saran wrap over these - if done properly it will keep the wrap off the frosting.
So long as there aren't any holes you can also freeze the cake in this manner (I've done it for a week, but heard you can do it for a month or so) - and defrost it overnight in the fridge.
Step 12: Let Them Eat Cake...
Share with your friends, coworkers, family... whomever!
I know if it were me (and currently it is) I don't need to eat it all myself, and by spreading the love you can get good feedback on how well you did too!