01 -
Place blueberries in a food processor and blend until mostly smooth, leaving small chunks for texture. Set aside.
02 -
Add softened butter, lemon zest, and a portion of the powdered sugar to a mixing bowl. Using a hand mixer or a stand mixer fitted with a whisk attachment, beat on low to combine, then increase speed to medium until the mixture becomes fluffy and smooth, about 2–3 minutes.
03 -
Add the blueberry puree and vanilla to the whipped butter mixture. Continue to beat until fully combined and airy, adjusting with the remaining powdered sugar and milk to achieve desired sweetness and spreadable consistency.
04 -
Serve immediately. For storage, transfer to an airtight container and refrigerate for up to 4 days. Allow to soften at room temperature before serving. For longer storage, wrap tightly and freeze for up to 6 months; thaw in the refrigerator overnight before use.