1 can sweet & condensed milk

*place can in small pot covering top of can with water. Boil for 3 hours, making sure can is always covered with water. You WILL need to add water during process.
Preheat oven to 350 degrees. Coat 2 (9") cake pans with cooking spray. On low speed, beat cake mix, eggs, 1 cup water and sour cream until combined, 30 seconds. On medium speed, beat 2 minutes. Evenly divide between pans. Bake 35 minutes or until toothpick inserted into center comes out clean. Cool in pans on racks 5 minutes. Remove from pans to racks.
With skewer, poke 15 holes into each warm cake layer, going halfway into cake. Spread ¼ cup caramel sauce over each layer, cool completely.
Place 1 cake layer on serving plate, spread with 1 cup frosting. Top with remaining cake layer. Spread cake top and side with remaining frosting. Drizzle cake top with remaining ¼ cup caramel sauce.