6 cups milk
1 (14 ounce) can sweetened condensed milk
2 cups semisweet chocolate chips
1 1/2 cups heavy whipping cream
1 teaspoon vanilla extract
Combine milk, condensed milk, chocolate chips, heavy cream, and vanilla extract in a slow cooker.
Cover and cook on Low, stirring occasionally, until chocolate chips are melted and mixture is smooth, about 2 hours.