Warning. This Instructable may get you married.

I swear, I get more offers off marriage off this chocolate sauce than anything else I ever make. And it takes ten minutes to make, has six or less ingredients, and turns that boring old vanilla ice cream in your freezer into instant gourmet. It's not even originally my recipe: it's based on Scott Peacock's, in his book The Gift of Southern Cooking with the late great Edna Lewis.

Mine's got easier instructions, ~~suggests using a Mars Bar instead of the chocolate for extra awesome~~, and substitutes maple syrup for granulated sugar, but respek where respek is due. It is, indeed, teh awesome.

Step 1: Ingredients

Ok. Gather your ingredients. You need

half a cup of heavy cream
half a cup of milk
3 oz of good dark chocolate ~~(or, if you're out of the US, a Mars bar. )~~ (See below.)
a tablespoon of butter
a sweetener: I like maple syrup. Honey's good. White sugar if there's nothing else.
a scant teaspoon of salt

Did you notice how you've probably got most of these around the kitchen already?

In my case, I'm using tasty raw, unpasteurized, unhomogenized milk from the cows that I co-own at the excellent Meadowsweet Farm. Which means that the first two ingredients are just representative samples of the top of the bottle and the rest of the bottle. If you don't have a good local dairy farm around to support, you could also just use a cup of half-and-half.

EDIT:
So I tried using a couple of Mars Bars I brought back from Canada the other day, and it was so painfully sweet, even without any added sugar, that I'm retracting this suggestion. I used roughly equal quantities of Mars Bar as I had dark chocolate, and it was too sweet for most of us to actually finish, and had the consistency of thick hot chocolate.

If you do want to use a Mars Bar, skip this recipe: just chop up your Mars Bar into a pan and melt it over the stove, stirring as you go, and pour that over ice cream when it's melted. It's still achingly sweet, but the consistency is better. You don't want to microwave it because the caramel absorbs heat a lot faster than the nougat and very quickly foams up in a huge way and scorches.

Step 2: Heat Up Your Moo Juice.

Mix together your milk and cream in a pan and heat up. *DON'T BOIL IT*

In this picture I'm putting in some maple syrup. You could. Or just wait till later.

Step 3: Melt Your Chocolate and Butter

First, take a knife and break your chocolate up into rough shavings. Just chop chop chop the side of your block of chocolate and it'll shave off nicely

Now, this is where you can choose how hardcore you are.

If you're good, you pull out a double boiler, gently melt your chocolate and butter in there. It looks like you know what you're doing, impresses the people you want to impress, and I think this way might give you smoother texture in the end.

If you're slack like me, you just throw the chocolate and butter in the microwave for 2 minutes and 22 seconds, and boom, you're done.

Step 4: Combine Milk/cream and Chocolate

If you're doing this the easy way, now you add your melted chocolate/butter mixture into your nicely warmed cream/milk mixture and stir until it's all mixed in.

If you're doing this the hard way, then you want to add your milk/cream to your chocolate sitting there on the double boiler, stirring all the while until it's all mixed in.

Step 5: Sweeten and Serve

Now mix in your sweetener to taste.

As mentioned, I like maple syrup, and it mixes better and quicker than granulated sugar. Honey is also good. But if sugar's what you've got, throw it on in.

Notice I'm not giving quantities, because it's all about what tastes right for you, and it also depends on your chocolate. I'm using 99% dark chocolate here, so that means you need more.

Serve over ice cream. Or cake. Or apple pie. Or cardboard, for that matter. It makes everything taste awesome. Put it in the fridge; it'll last for ages -- Scott claims 3 weeks. Just turn down those marriage offers. Ain't no basis for a long-term relationship, y'know.