Soften the cream cheese in the microwave for 15 seconds. In a mixing bowl, combine the softened cream cheese with sugar, cocoa powder, peanut butter powder, and vanilla extract. Mix until the ingredients are mostly combined.

Pour in the milk and heavy cream into the mixture. Using a whisk, stir everything together thoroughly until well-combined and smooth, ensuring the mixture is free of lumps.

Transfer the creamy mixture into the Ninja Creami pint container, packing it gently but tightly. Place in the freezer for a minimum of 24 hours.

After the freezing time, take the container out of the freezer and fit it into the Ninja Creami machine. Process on the ice cream setting until smooth; if too firm, add a splash of milk and reprocess.

Create a small hole in the center of the processed Ninja Creami. Add your choice of mix-ins and activate the mix-in feature to distribute evenly.