This caramel sauce owes its smooth, glossy sheen and pourable consistency to a bit of heavy cream and butter.
Place sugar and 1/2 cup water in a saucepan; stir. Then cook, without stirring, over medium heat until boiling. Occasionally wipe down sides of pan with a wet pastry brush to prevent stray granules of sugar from crystallizing. When sugar just begins to brown, swirl pan; cook until sugar is a rich amber color. Reduce heat to low; gradually add cream while stirring with a wooden spoon. Add butter and lemon juice; combine. Serve (or store in an airtight container, refrigerated, up to a week, and warm before serving).