- Beat cake mix, 1/2 cup of butter, water and eggs in large bowl at medium speed until smooth. Set aside for 30 minutes.
- Preheat oven to a temperature of 400°F. Grease cookie sheets.
- With the help of rounded teaspoon, drop batter on cookie sheets leaving 2 inch space in between. Sprinkle dash of salt on each of them.
- Bake for 5-7 minutes or until toothpick inserted in center comes out clean. Transfer to wire rack to cool.
- Beat remaining butter in a medium bowl at medium speed until creamy. Reduce speed to low; slowly add sugar and beat until combined.
- Add caramel sauce, a teaspoon of salt and vanilla extract, keep beating to mix well.
- Fill the mixture into a piping bag or use a teaspoon to spread filling on surface of a cookie, place second cookie, bottom-side down over filling. Follow the same process with remaining cookies and filling.
- Serve warm or chilled, as you like!