Show off your love for things retro and geeky with an edible armada of space invaders. This instructable will take you through the steps of making a simple chocolate candy using a silicon mold.

For Xmas last year, my better half surprised me with a spunky turquoise ice tray produced by ironic home goods designer FRED, inspired by the Taito arcade classic that we know and love. Space Invaders! After the novelty and enjoyment of freezing water, juices, coffee, and regular old liquids wore off, I set my sites on putting this gift to a higher purpose.

Chocolate.

That's right, after a few test runs and brushing up on some elementary chocolate making theory, I was able to pull off in time for V-day the perfect display of geek love - a chocolate 8-bit sprite.

Step 1: Tools and Ingredients

The Mold
First and foremost, one needs to acquire a mold. I opted to use the Ice Invaders ice tray, but really any flexible silicone mold/tray could be used to shape chocolates. You could even use a clear plastic candy mold, but in my opinion silicone are more durable and easier to work with.

If you do plan on going the space invader route, you could try to find one locally or online. We bought ours in Japan, but I have seen them available on Amazon or at ThinkGeek (naturally). The downside of these is that they are on the small side so if you're going to make lots of chocolates you might need to pick up more than one to speed things along (there are 24 molds in each tray). Moreover, they don't match the original Space Invaders sprite to the pixel, but they do get the point across rather well.

And if you're wondering, I'm not affiliated with either site above or the manufacturer, FRED. I do appreciate the sense of humor they bring to their product design though, and consider this a quality product.

The Ingredients
1) Chocolate - For this 'ible I went with a Japanese dark chocolate that was available, but any type will work. Milk, Dark, White - go with your personal preference. Remember, better quality chocolates will make for a better tasting Space Invader.
Pictured are two 58 gram chocolate bars (roughly 2oz each). To fill the entire mold I would recommend at least 3 bars of chocolate, and if you're making solid chocolates possibly 4 (8oz or 232 g)

2)Filling - For the sake of simplicity I went with solid dry ingredients: almonds and dried blueberries.
If you were to use a creme filling, caramel, cordial, or a truffle ganache it would require a bit of a different method (painting a shell and so on). Since this is my first attempt at confectionery, I thought the Invaders would be too fragile to hold up that well as a shell. I decided to stick with fillings that will provide a strong structural center. Blending in flavourings such as vanilla, sea salt, and chili pepper work well too. Get creative and adventurous.

The Tools
Here you have plenty of freedom to improvise, but this is what I had to work with:
1) Cutting board (flexible is a plus)
2) Sharp kitchen knife
3) Silicone spatula (rubber is fine too)
4) Squeeze bottle (thinner spout the better) - alternatively you can use a pastry bag.
5) Stirrer (I used some disposable chopsticks)
6) Microwave (or double boiler) & microwave safe bowl (ceramic is a plus as it retains heat well)
*If you have one on hand, an electric kitchen thermometer is helpful, but not really necessary.

Now that you have all of the items assembled, go find a cool dry space in your kitchen to get to work.

Step 2: Make 'em Melt

The first order of action is to render those chocolate bars down to a primordial soup of sugar, cocoa solids and cocoa butter.

Shaving
To get things started take your knife and cutting board and begin to gently shave the chocolate bars down into flakes and chunks. Breaking the chocolate down to smaller pieces will allow it to melt more evenly and will shorten the time needed to heat it. Go slowly, and don't chop or slice the chocolate; rather, push down slowly with your weight and it should come off in flakes and chunks. Run your knife through the flakes if you find they're too chunky and then transfer to a microwave safe bowl. When you're about 2/3 of the way through with the chocolate save the rest and set it aside - we'll come back to it later.

Nuking
Take the shaved chocolate to the microwave and nuke it on high in 30 second blasts, stirring well in between each interval so that the chocolate heats evenly. If you microwave it at longer intervals the chocolate may overheat and start to burn - be patient and things will go smoothly.
Once the chocolate gets to the point where it is melted but still chunky, continue at 15 second intervals, mixing well in between. As soon as the chocolate becomes smooth and chocolate-saucey looking you're done. You can check by dabbing a bit on your skin and seeing if it's warm (not hot) to the touch - we're looking at something around 105°F or 41°C which is a little bit above body temperature.

Alternatively, you could do all of this in a double boiler, but if you were the type of person to own a double boiler you wouldn't need to read this instructable, now would you?

Step 3: Watch Your Temper

At this stage we have melted chocolate - a state in which the crystalline structure (surprise! chocolate crystals!) of fat and sugar that makes chocolate so damn delectable have all broken apart and rearranged themselves. At this point we temper the chocolate, a process that ensures the molten chocolate hardens and sets correctly, and improves the texture and melting point of the finished chocolate.

To achieve this, I opted to use a method referred to as seeding. To seed chocolate, you take unmelted chocolate to your warm, melty chocolate and have them co-mingle. Remember that extra chunk I asked you to hang onto? Add that bit into the bowl and stir it in until it is fully incorporated. Continue stirring it slowly. Once the chocolate starts to thicken up a little bit, and feels tepid to the touch, then your at the temperature where tempering occurs (88° - 93°F depending on the chocolate, or just a bit below body temperature).

The aim is to keep the chocolate at this temperature while stirring it around, so that the proper crystals can form. This is difficult to do accurately without a thermometer so I would just say eyeball it and keep stirring; if the temperature drops and the chocolate becomes too thick, give it 5 seconds in the microwave or so to warm it up a bit.

To be honest, the whole science behind tempering chocolate is well beyond my expertise, but there is a great walkthrough on Cooking For Engineers that explains it much better than I can.
In simple terms: melt chocolate, add chocolate, stir, not too hot, not too cold.

Step 4: The First Layer

Having tempered your chocolate, you can now begin to fill the molds. Make sure that the silicone mold is clean and bone-dry; chocolate and water are not friends.

First, scrape the chocolate out of the bowl into the squeeze bottle with the spatula. Work quickly and make sure that the temperature doesn't drop too much.

Then, squeeze a small dollop of chocolate in each mold that you are going to fill.

Lastly, lift the tray with your finger and let it lightly fall back to the counter so that the chocolate spreads out into the cracks or the mold. Continue tapping the tray in this fashion until the bottom of the tray is covered in an even layer. Pull at the edges of the tray to stretch the silicone so that the chocolate can get into all of the corners of the mold - the legs and antennae are the most difficult parts to get filled, so if it's not working out use a toothpick to shovel chocolate in there.
[I was working a bit too quickly and forgot to photograph this step]

If your chocolate starts to get too thick, a quick 5 sec burst in the microwave should do the trick.

Step 5: Go and Stuff It!

Now is the time to add your fillings. Again, work quickly to keep the chocolate from seizing up too soon. Place each filling into the mold cavity on top of the layer of chocolate at the bottom. Make sure that the ingredients are small enough to fit in the mold without touching the sides or sticking too far above the tray, otherwise you won't get full coverage throughout the entire mold, and you'll end up with a mutant Invader (which is cool if that's your angle). Give it a few more taps and pokes so that the filling sinks into the center of the mold.

If you were to do a creme filling, you would take a "decorator's" brush and paint the floor and walls of the mold with tempered chocolate, chill them, repeat, and then fill the chocolate shells with your filling. I'd fill the legs and antennae with solid chocolate though, as these are the most fragile parts.

Step 6: Topping Off

Now that each mold has been filled, top off the rest of the mold with the remaining tempered chocolate. This is the messiest part, so my approach was to add a second dollop on top of the filling and then continue tapping and stretching the tray until the chocolate evened out. Keep an eye on the amount of chocolate as well - you want to have it be level or slightly under the top of the tray. Once it spills over the top of the molds the Invader will start to look a bit unfinished and messy.

Continue this process while keeping the chocolate at temperature until air bubbles stop forming on the surface of the chocolate.
Lastly, wipe the surface of the tray so the edges of the mold are clear of excess chocolate.

TIP: That messy squeeze bottle can now be cleaned by pouring hot milk into it, giving it a few shakes, and squeezing out a rich hot chocolate.

Step 7: Chill Time

Now that the molds are filled and the chocolate is evenly spread and free of bubbles, park that tray in the fridge or freezer and go relax.

Chocolate in the fridge? Don't freak out. It'll only be in there for about 5 - 10 minutes or so until they set up and harden.

If you have a cool area in your kitchen you can also cool the chocolates on the counter top. Either method will produce good end results. However, don't leave the chocolates in the fridge for too long or else oil will bead up at the surface and give the backs of your chocolate a 'sweaty' appearance (and there's nothing appetizing about sweaty backs, am I right?)

Step 8: Breaking the Mold

Once the chocolate has hardened you can liberate your Invaders from the tray and unleash them on an unsuspecting planet.

To do so, simply pull on the edges of the tray at each row and column to release the chocolate from the sides of the mold. Then gently push directly up on the bottom of the mold so that the chocolate is pushed straight out of the mold. Trying to pry them out at an angle will most likely result in a broken leg and a sorry looking Invader. However, the great thing about silicone is how stretchy and bendy it is, so with a little care they should pop right out.

Step 9: Commence the Invasion

Now that you have a finished set of Invaders you can send them out to bombard your Valentine with sweet, geeky love. Or you can eat them by yourself while playing Xbox Live. (tastes better that way!)

For plating, arranging them face up in regular Space Invaders gameplay fashion is classic.
For gifting, reusing boxes from commercial chocolates do the trick very nicely.

Thanks for checking out this Instructable. Any comments or suggestions are welcome. And if you enjoyed it, please vote for it in the Valentine's day contest (Update:Thanks for the votes! I was elated to find out that this made the finals! And thanks to the Instructables team for the newsletter feature and building such an awesome community.)