Preheat oven to 350°F/177°Grease and line a 6-inch round pan. Set aside.
In a bowl, mix together butter, eggs, water, and cake mix.
Pour cake batter into prepared cake pan.
Bake in the preheated oven for 18-20 minutes or until cake is set and lightly golden brown. Let it cool. And set aside.
Prepare caramel sauce, in a small nonstick saucepan, melt brown sugar, once melted carefully pour in cream. Mix until sugar is dissolved, mix in butter and vanilla. Stir until smooth.
Transfer cooled cake in a 6 x 2.5- inch tin can.
Pour prepared caramel sauce onto cooled cake, top with salt. Serve