1. Preheat the oven to 350°F and grease a 9×13-inch baking dish.

2. In a large bowl, mix the yellow cake mix, eggs, water, and vegetable oil until smooth.

3. Pour the batter into the prepared baking dish and bake for 28 to 32 minutes, or until a toothpick inserted in the center comes out clean.

4. Let the cake cool for about 10 minutes.

5. Use the handle of a wooden spoon to poke holes all over the top of the warm cake.

6. Pour the sweetened condensed milk evenly over the cake, making sure it seeps into the holes.

7. In a small bowl, stir together the brown sugar, ground cinnamon, and melted butter.

8. Spoon the cinnamon mixture over the cake, spreading it across the top and into the holes as much as possible.

9. Let the cake cool completely.

10. In a mixing bowl, beat the cream cheese and softened butter until smooth and creamy.

11. Add the powdered sugar and vanilla extract, then beat until fluffy.

12. Mix in the milk until the frosting is smooth and spreadable.

13. Spread the frosting evenly over the cooled cake.

14. Chill for at least 1 hour before slicing and serving.