Preheat oven to 350°F. Butter a 12-cup Bundt pan. Spread room temperature caramel sauce over bottom and half-way up the sides of the pan; set aside.
Cream butter and sugar. Beat in eggs.
Stir together flour, cocoa, baking soda, salt and ground coffee. Add dry mix in portions to creamed mixture alternating with buttermilk and coffee liqueur. Mix until well blended. Spread batter evenly into prepared Bundt pan.
Beat eggs. Whisk in sweetened condensed milk, evaporated milk and vanilla. Slowly pour over cake batter.
Set Bundt pan in roasting pan and add about an inch of hot water to roasting pan to create a water bath. Bake one hour.
Remove Bundt pan from water bath and let cool about 15 to 20 minutes.
Invert a large rimmed serving platter over pan and flip to unmold. Cool at room temperature about an hour then refrigerate.
Dulce de leche or cajeta can be found in the Hispanic food section of grocery store.