Preheat your oven to 350°F (175°C). In a large mixing bowl, combine the red velvet cake mix with the ingredients listed on the box, usually water, eggs, and oil. Mix according to package instructions until smooth.
Pour the cake batter into a greased 9x13 inch baking dish. Bake in the preheated oven for 28-30 minutes or until a toothpick inserted into the center comes out clean. Allow the cake to cool for about 15 minutes in the pan.
Once the cake has cooled slightly, use a toothpick or skewer to poke holes all over the surface of the cake, about 1 inch apart. Be careful not to poke all the way to the bottom; just create enough holes to allow the condensed milk to seep in.
In a small bowl, pour the sweetened condensed milk over the cake, ensuring it fills the holes you've poked. Let the cake sit for about 30 minutes to absorb the condensed milk.
In a mixing bowl, beat the softened cream cheese and unsalted butter together until light and fluffy. Gradually add in the confectioners sugar, vanilla extract, and salt. Mix until smooth and creamy.
Spread the cream cheese frosting evenly over the top of the cake, making sure to cover it well. Sprinkle mini semi-sweet chocolate chips on top for extra sweetness and texture.
Refrigerate the cake for at least 1 hour before slicing. Serve chilled and enjoy!