Combine the heavy cream, cocoa powder and sugar in a medium saucepan and whisk to combine. Set over medium heat and, whisking frequently, bring to a boil. Turn off the heat, add raspberries, cover and allow to sit for 10 minutes.

Using a blender, immersion blender or food processor, purée the mixture until smooth. Set a fine mesh strainer over a bowl and pour the mixture through it to remove any seeds. Cover and refrigerate until completely cool (I let mine cool overnight). Once cool, the mixture will be quite thick. Freeze in an ice cream maker according to manufacturer’s directions. Transfer to an airtight container, stir in the chocolate chips (if using) and store in the freezer to freeze completely.