Add sugar (and water if using) to a medium saucepan over medium heat. Let it melt without stirring.

Once edges start turning golden, gently swirl the pan until all sugar melts and deepens in color.

Add butter carefully and whisk until melted and combined.

Slowly pour in heavy cream while whisking constantly — the mixture will bubble up.

Remove from heat and stir in salt.

Let cool slightly before transferring to a jar. Store refrigerated up to 2 weeks.