Heat the Sugar: In a medium saucepan over low-medium heat, add the muscovado sugar and let it begin to dissolve. Stir occassionally to help it melt evenly, but be careful not to stir too much to avoid crystallization.
1 cup muscovado sugar
Add the Butter: Once the sugar is mostly melted and bubbling, add the butter pieces one at a time, stirring to combine. The mixture will bubble up, so be careful.
3 tablespoons unsalted butter
Pour in the Condensed Milk: gradually add the condensed milk while stirring. Be cautious, as the mixture may bubble. Keep stirring until it’s well incorporated and smooth.
¼ cup condensed milk
Simmer and Thicken: Allow the sauce to simmer over low-medium heat for 2-3 minutes to thicken slightly. The sauce will continue to thicken as it cools, so don’t overcook it.
Add Vanilla and Salt: If using, stir in the vanilla extract and salt. These will enhance the flavor and bring out the caramel’s richness.
pinch of salt, ½ teaspoon vanilla extract
Cool and Serve: Remove from heat and let the muscovado sauce cool for a few minutes. Pour it into a heatproof jar or container. The sauce will thicken as it cools.