Toffee

In preparation for this season's Christmas parties, I've taken to making toffee.  The first time it didn't turn out well (I had the heat too high, and the butter separated), but the next two times have gone great.  Here's how it works:

Ingredients:
4 sticks (2 cups) butter
2 cups white sugar
1/2 teaspoon salt
1 teaspoon vanilla
12 oz quality chocolate (we used Ghiradelli semi-sweet)
1 cup chopped nuts (almonds, pecans or walnuts - they all taste pretty similar)

How to put it together:
Put the butter into a large saucepan on medium (NOT medium-high) heat.
After it starts to melt a bit, add the sugar and salt, stirring until the butter is melted.
Once the butter melts, you'll want to almost leave it alone.  The butter will start to foam. Only stir if you see clumps of sugar, or dark spots.  It will look like this at first:

While this is cooking, run the nuts through a food processor, then run the chocolate through a food processor.
Keep cooking the butter/sugar until it looks about like this:

Pull it off the heat, and pour this toffee part onto a jelly roll pan lined with aluminum foil, parchment paper or a silpat.
Sprinkle the chocolate over the top, and after it melts for a minute, smooth it out with a spatula.
Sprinkle the nuts over the top, and use a spatula to press them down into the chocolate.
Let this harden, crack it up and you're good to go.  The final result will look something like this: