In a medium saucepan over medium heat, combine the blueberries and 2 tablespoons of water. Cook for about 5-7 minutes, stirring occasionally, until the blueberries have burst and released their juices.

Remove the saucepan from heat and let the blueberry mixture cool slightly.

Once cooled, transfer the blueberry mixture to a blender or food processor. Blend until smooth.

In a mixing bowl, combine the softened butter, powdered sugar, vanilla extract, and salt. Beat with an electric mixer until creamy and well combined.

Gradually add the blueberry puree to the butter mixture, mixing until fully incorporated and smooth.

Transfer the blueberry butter to a serving dish or airtight container. Chill in the refrigerator for at least 1 hour to firm up before serving.