• In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and confectioners' sugar on medium speed until smooth and well combined, about 1-2 minutes.
• Add the milk. Slowly increase the mixer speed to high. Whip on high for 5-7 minutes, stopping to scrape the sides of the bowl as needed, until the mixture is light and airy.
• Add the blueberry jam, lemon zest, and salt. Mix on low until fully incorporated, about 1 more minute.
• Serve immediately on pastries, pancakes, or toast. Or, make it into a compound butter.

Lemon Blueberry Compound Butter

• To make a compound butter, scoop the blueberry butter onto a piece of plastic wrap. Roll the butter into a log shape, pressing and shaping as you go. Twist the ends of the plastic wrap together to secure the log, and refrigerate until firm (at least 2 hours or up to overnight).