In the bowl of a stand mixer with the paddle attachment, cream your butter on medium-low speed for 3-4 minutes.
Add in your caramel sauce, vanilla, and salt. Mix on low speed until combined.
Gradually add in 2 1/2 cups confectioner's sugar, along with the 1/2 tbsp of heavy cream. If the frosting is too runny, add up to an additional 1/2 cup of confectioner's sugar.
Pipe your frosting onto approximately 10-12 cupcakes or a small square cake (the number cupcakes depends on how thick/tall your frosting is).
Notes
For the caramel sauce, I used the Pioneer Woman's caramel recipe. Any homemade caramel sauce can be used though, and if you're in a pinch, store-bought would probably work fine.