Polar Express Hot Chocolate

6 cups milk
1 (14 ounce) can sweetened condensed milk
1 1/2 cups heavy whipping cream
1 1/2 cups bittersweet chocolate chips
1 teaspoon vanilla extract
1/8 teaspoon salt

Combine milk, sweetened condensed milk, cream, chocolate chips, vanilla extract, and salt together in a large pot over low heat; cook, stirring constantly, until chocolate is melted, 30 to 40 minutes.