- 10 ounce bag of frozen blackberries, thawed
- 1 cup butter, softened
- 1/2 cup shortening
- 1 tbsp pure vanilla extract
- 1 pound box powdered sugar
- Using a blender, puree the blackberries. Pass the puree through a sieve, discard the seeds left behind and set seedless puree aside.
- In the bowl of an electric mixer, cream the butter and shortening until fluffy, about 1 minute.
- Add the vanilla and the blackberry puree to the butter mixture and mix until homogenous, about 2 minutes. Add the powered sugar, 1 cup at a time, until fully incorporated.
- Use to frost an 8-inch cake or 12 cupcakes.