1 cup sugar
1/4 teaspoon salt
1/4 cup water
1/2 cup heavy cream
2 Tablespoons unsalted butter
1/2 teaspoon pure vanilla extract
In a small saucepan, combine sugar, salt, and the water.
Cook over medium heat until sugar is a medium amber color (use strips of paper to test: the paler color is undercooked; the amber hue is just right), about 7 minutes; wash sides of pan with a pastry brush dipped in water to prevent crystals from forming.
Remove from heat.
Stir in heavy cream; add butter, and stir until combined.
Let cool to room temperature.
Stir in vanilla.
Source: Martha Stewart; posted by LuAnn for KRT.