STEP 2: Once you’ve let your butter come up to room temperature (if you can easily press into it and leave a noticeable divot, your butter is good to go), add it to a large bowl with the powdered sugar and salt. You can mix this by hand, in a stand mixer with the paddle attachment, or with electric beaters. Just make sure everything is combined and smooth.

Source: https://www.buzzfeed.com/claudiasantos/chocolate-salami-recipe