Add sweetened condensed milk, chocolate chips, and 4 cups hot water to slow cooker. Cook on high 55 minutes, whisking every 15 minutes. Test taste, adding more water until desired sweetness is reached.

Meanwhile, heat pot over medium-low heat. Add raspberries, mint and 3 Tbsp. water. Simmer about 5 minutes, or until it reached a sauce-like consistency.

Use mesh sieve to strain seeds from sauce, pressing through with the back of a spoon. Set aside to cool.