This is a two-layer pie with a coffee shortbread crust. The bottom layer is a light chocolate ganache, and the top layer is a coffee custard. Nice and light, cool and creamy. Here we go!

Ingredients:

Crust:

1/2 Cup butter

1/4 Cup brown sugar

1 Cup flour

spoon or two of coffee.

Ganache:

1/2 Cup to 1 Cup Chocolate chunks

1 Cup cream

Coffee Custard:

4 egg yolks

1 Cup coffee (strong!)

1 Tbsp white sugar

1 Tbsp cornstarch

Tools:

Pie pan

Whisk

Small pot

Bowls

Notes on Ingredients:

Use the strongest coffee you can make. Espresso would be best, and if I win the Caffeine Contest I will surely do some experiments! I tried a couple methods, including boiling some coffee down, which is terrible. Use instant or a moka kettle or a french press for best non-espresso results.
Why use brown sugar in the crust? Because it's delicious. And for things like a crust, I think it helps hold together.
For the flour in the crust, I used a mix of all-purpose and wheat pastry. This was my first time ever using a pastry flour, and it worked great!
Use the best chocolate you can get your hands on, within reason. I mixed toll-house chocolate chips with some bittersweet scharffen-berger. It's good.
For the custard, the cornstarch may not be necessary, if you use more yolks or less fluid or have different humidity, moon phase, I don't know. I needed it and could've used a tad more.
The custard may take some time to set. In my last pictures you see if flowed a bit, because I cut the first slices on the same day. Let it sit in the fridge overnight and the custard will stiffen.

Step 1: Make Thee Some Strong Coffee

You will only need about 1.5 cups. Espresso would be best, but you can also use a french press, moka kettle, or whatever you've got.

I tried making it strong by mixing it in a bowl, pouring it through the filter of my coffee maker, and boiling it down. Don't do that, it makes real bad coffee. Access to a moka kettle saved me.

Step 2: The Crust

The crust is real easy. Easiest crust I've ever made, seriously. Turn the oven to 350ºF (177ºC), we're gonne pre-bake it.

Just mix all the ingredients, add as much coffee as needed to keep it together and add a bit of coffee flavor, and gather it into a ball. Smush the ball into a pie pan and flatten it out with your (clean!) hands, pushing it up the sides and forming a little rim. Once it's formed, it helps to chill it in the freezer to harden the dough a little. While it's chilling, work on the ganache and custard.

Line the dough with aluminum foil. This will keep it from drying out too quickly and browning too early, as well as bubbling up and melting down the sides. I've had messes from pre-baked crusts in the past. So use foil, and fill it with dry rice, which will weigh the foil down. Use the rice to weigh down the bottom and sides. Some people have special pie weights, and some people use beans, but baking can give beans an off flavor, while the baked rice can be used for anything other rice can. Pie weights would be great if I baked pie every day, but I don't.

Bake the crust for 20 minutes with the foil and rice. Then take it out, and lift out the rice by grabbing the four corners of the foil. Don't spill it or you'll be stepping on it for weeks. The crust should look wet on the bottom but dry on the rim and some of the side. If it's too wet, leave the rice on it and give it a couple more minutes. While it's baking, work on the ganache and custard.

Bake it again without the foil or rice, for about 10 minutes. Just a bare crust. It should be nice and golden-y brown. I've got to work on my food photography, I guess, because it looks better in person, I swear. My food looks great, but my pictures are not food blog material.

Crust done!

Step 3: Chocolate Ganache

So, the chocolate ganache is also just really really easy, and barely takes time at all. Heat the chocolate in the microwave for 10-20 seconds at a time until you can see it is just barely starting to melt. Then leave it.

Warm the cream in the microwave until it's warm to the touch. It may get a skin on top, but it'll mix right in. And here's the beautiful step that makes ganache so awesome and easy.

Pour the cream over the chocolate. Don't mix it, just leave it be.

After a couple minutes, the cream will have mostly melted the chocolate. Then stir it well. It'll look funky for a bit and then it'll look beautiful. That's it.

If it doesn't all melt, give it a quick zap in the microwave. If it's warm enough but still a little gritty-looking, let it rest for a minute and stir it again.

You can make it thicker by using more chocolate and less cream or thinner by using less chocolate and more cream.

Once it's a beautiful chocolate soup, pour it into the finished crust and let it cool. You could probably hurry it along in the fridge or freezer.

Step 4: Coffee Custard

This is a stirred custard, which means you stir it in a bowl over a hot water bath. That cooks the egg yolks, and thickens it to a custard-y consistency.

Start by separating your yolks. I like to crack the egg over my whites bowl and pour the yolk from one half of the shell to the other and back until the white has fallen off. You can use the shell to scrape those stringy white bits off, they're better off with the whites. We don't use the whites for this recipe, but it could be made into a meringue topping for this pie, for other pies, for meringue cookies, or to fluff up some tasty waffles.

When you've got the yolks in their own bowl, whip 'em up. Add the sugar and whip. Then add the coffee and cream and whip. If the coffee is hot, add it last, and very slowly while whipping the mixture, or it may cook and curdle the yolks and nobody wants that.

After it heats up (around 170ºF, if you're keeping track) it should thicken a little. Then mix the cornstarch with a small amount of cold coffee (or water), stir it up, and add it in. Keep mixing constantly, and within 3-5 minutes it should thicken into more of a thick soup consistency. That's a good time to call it done. Take it off the heat and let it cool.

Once cool, add it to the pie! Pour gently so it doesn't disturb the soft ganache, and it'll make a nice soft layer. If your custard is thicker you might want to pour it while it's warm, but take more care because that will mix more with the ganache, and could leave streaks. Not a bad result, just less uniform.

Let it cool and set overnight in the fridge for best-looking results and more solid pie.

Step 5: Enjoy!

I sprinkled some chocolate shavings on top to make it pretty. I couldn't wait until the next day, so I just dug in. As you can see, the custard was still a bit soupy, but it set right up the next day. I also put some extra into a mug for cute-ness and an alternative serving suggestion.

That's it! You can do a lot with ganache and shortbread skills, and custard can be done many ways, though it's often baked.

More Thoughts:

The ganache could be made with coffee instead of cream to add to the coffee flavor of the dish. Again make it as strong as possible and use espresso if you can. This would be a type of "water ganache," which is known for making flavors really pop. Less shelf life though, so don't save it for too long.
Espresso would be the best coffee choice for all steps in this pie. By the way, feel free to vote for this instructable in the Caffeine Contest!
The custard could be made thicker. You can do this by 1) adding more egg yolks, 2) adding more cornstarch, or 3) reducing the amount of liquid added (by using a smaller amount of more concentrated coffee). If you decide to make it thicker, do everything in the same order, but pour it into the pie when it's still warm, before it gets too thick.
This could also benefit from some almonds, hazelnuts, or similar good mocha-compatible flavors. Ground nuts could be easily worked into the crust without affecting much else.

Good luck! Let me know if you make it and if you have any questions!