Add the mascarpone, agave, vanilla and salt to the bowl of an electric mixer.
Mix for about 1 minute until creamed together and combined and add the heavy cream to the bowl.
Mix again on medium-high for 30 seconds to 1 minute until the frosting is fluffy and smooth.
Transfer the frosting to a plastic zip-top bag or frosting piping bag. If you’re using a plastic zip-top bag, use scissors to cut off one corner to easily pipe it.
Pipe the frosting onto whatever your heart desires (I made cupcakes :)).