In a large saucepan on medium-high heat, stir ingredients together.
Heat for about five minutes, whisking occasionally, until the mixture begins to boil.
Turn the heat down to medium, and continue whisking frequently.
Be sure to whisk away the “foam” that appears.
Once this foam is completely gone (about 13-14 minutes), cook for another minute, whisking constantly.
This will bring the cooking time to about 20 minutes total.
The dulce de leche will have thickened to a caramel-like consistency and will be a medium golden color.
Let cool for about ten minutes before either using or transferring to a heat-safe jar and continuing to cool, uncovered, in the fridge.
Once cool, cover and store.
To store: Refrigerate in a sealed jar for up to two weeks.
To reheat: Scoop the caramel into a small saucepan on low heat and gently heat for about five minutes, whisking occasionally, until the caramel becomes smooth and pourable.