Slow cooker dulce de leche (Cajeta) (gluten-free)

Dulce de leche (”milk candy” ;) is a milk based caramel type sauce which was popularized in South American countries. This recipe is similar to the Mexican ‘cajeta’ which uses 1/2 goat milk and 1/2 cow’s milk.
You can buy dulce de leche, but why buy canned dulce de leche? Its SO very, very easy to make. [...]