This is a relatively thin sauce - very pourable - but when you pour it over cold ice cream to serve, it will get thicker. If the sauce was thicker to begin with, it might be too thick on the ice cream.

Sugar is a tricky thing to work with. In theory, you don't need to add the water - you can melt sugar in a dry pan. If you're super-confident, you can do that. But sugar burns easily, and there's always the risk that you'll burn some of the sugar before the rest is completely melted, and then you’ll have to start over again. Burned sugar is bitter.

Makes About 1 pint

• 1 cup sugar
• 1/4 teaspoon salt
• 1/4 cup water
• 4 tablespoons butter
• 3/4 cups heavy cream
• 1 teaspoon vanilla extract

1. Put the sugar, salt, and water in a heavy bottomed-pot with a lid. Slap the lid on and turn the heat up to medium, or just a bit lower. Cook until the sugar is melted - you'll know because the liquid will be completely clear. It might be turning a little golden, but it won't be cloudy.
2. Meanwhile, combine the cream with the vanilla and set aside until you need it.
3. Take the lid off and continue cooking. Don't stir it, just leave it be. Cook until the mixture turns a nice amber color. Even though you're not touching it, you do need to watch it - the sugar can go from nicely browned to burned in a heartbeat.
4. Add the butter and whisk it in completely. The mixture will foam up. That's fine.
5. Turn the heat off and add the cream, whisking as you go. The mixture might seize up for a while, but it will smooth out again. If you need to, you can turn the heat on again to get it all completely combined.
6. Let it cool a bit, then transfer it to a container for storage. A pint canning jar works well. Keep refrigerated.