Okay, after you described what the cake is like, I just looked at a lot of recipes where you used Sweetened Condensed Milk, Caramel topping and CoolWhip -and also poked holes in the cake. See if this is similar enough so that you can make a Caramel Latte Cake for your husband's birthday. This one is called "Holy Cow Poke Cake". Someone who reviewed the recipe said that it is just as good without the candy bits on top. Let me know if this is sort of what you are looking for -and if you make it let me know if it is as good as you and your husband remember. AtlantaPat 
Holy Cow Poke Cake (Ready in 1-2 hours)
Ingredients:
1 package German Chocolate (or Milk Chocolate) Cake Mix
1 jar Caramel ice-cream topping
14 ounces can of Sweetened Condensed milk
4 Butterfinger (or Heath Toffee Bars) candy bars (optional)
8 ounces package Cream Cheese, softened
8 ounces Cool Whip
Directions:
Prepare cake as package directs. Bake in a greased 9"X13" cake pan at 350 degrees for 30-35 minutes (or until cake tests done).
Blend together the caramel topping and Sweetened Condensed milk.
As soon as cake is removed from the oven, take a straw, or back of a wooden spoon and poke holes all over the top of the cake. Pour caramel and condensed milk mixture all over the cake. If using the candy, crush 2 Butterfingers (or Toffee Bars) and sprinkle over cake. Chill cake.
Stir together Cream Cheese and Cool Whip until well blended. Spread over cake. Crush remaining candy bars and sprinkle over cake, if desired. Serves 12. Sounds good to me! 