One pan cake 

2 1/2 cups all-purpose flour
1 1/2 cups sugar
1/2 cup cocoa
1 cup salted caramel bar, chopped
2 tsp baking soda
1/2 tsp salt
2/3 cup oil
2 TBS cider vinegar
1 TBS vanilla
2 cups cold coffee or water
8 oz. whipping cream
¼ cup powdered sugar
1 tsp. vanilla extract

Preheat oven to 350 degrees.
Stir together flour, 1 1/2 cups sugar, cocoa, baking soda and salt in an ungreased 13 x 9 baking dish. Make 3 wells in the mixture; pour oil in one, vinegar in one and vanilla in one. Pour in coffee, salted caramel chips, and stir all with a fork until well mixed. Spread into an even layer. Bake in a 350 oven for 35-40 minutes. Cool 15-20 minutes before cutting. Top with salted caramel sauce (see below)
Salted caramel sauce:
1 cup sugar
1/4 cup water
3/4 cup heavy cream
3 1/2 tablespoons unsalted butter
1 teaspoon sea salt

In a heavy-bottomed saucepan, combine the sugar and water over medium-low heat until the sugar dissolves. Increase the heat and bring to a boil, without stirring. If necessary, use a wet pastry brush to wash down any crystals on the side of the pan.
Boil until the syrup is a deep amber color, about 5 to 6 minutes. Remove the sugar from the heat and carefully whisk in the heavy cream. The mixture will bubble. Stir in the unsalted butter, and salt.  Cut cake and serve with Salted Caramel Sauce spooned over the top.