Give this a try. Damn good beer for the price.
https://www.midwestsupplies.com/simply-beer-stout
Add a pound of lactose the last 10 minutes of the boil.
Last summer I did a blackberry wheat beer using fruit puree. I fermented in primary for a week, then racked onto the puree in secondary. Let it sit on the fruit puree for two weeks before bottling. Taste tested the beer prior to bottling to find that the blackberry flavor was very subtle...