You can also make this compound butter mixing by hand. Just make sure you smash the roasted garlic and finely chop the sun-dried tomatoes first. This butter tastes best if you let it rest for the flavors to meld together.
In a food processor, add the sun-dried tomatoes and roasted garlic. Pulse a few times until they start to break up and become more of a paste. If your food processor is large, it may not reach the ingredients very well. This is fine, they will continue to be processed later.
To the tomatoes and roasted garlic, add the remaining ingredients. Make sure the butter has been softened to room temperature so that it blends well.
Process until all ingredients are incorporated, approximately 30 seconds. Do not pulse too long or else the butter will start to solidify.
The butter will be warm and soft at this point. You can serve it as is, or you can let it chill.