I'm asking because I found a recipe online for an ice cream that calls for baking coco, but doesn't call for cooking. I've used baking coco before to make hot chocolate, but it seems that it wouldn't dissolve fully if not first put in some sort of hot liquid, even though it's finely ground. If not, do I need to treat it differently before putting it in a recipe?
Most of the ice creams I've made have been custard-based, meaning that egg yolks are cooked together with cream and sugar. The mixture is chilled and then churned. For a custard-style ice cream recipe including cocoa powder, the cocoa would likely be dissolved during the cooking step.
If you are following a no-cook recipe that includes cocoa powder, I would at least use a whisk to mix the cocoa in as thoroughly as possible. However, dissolving the cocoa in a hot liquid would likely result in a smoother ice cream.
Not sure what kind of recipe you are following, but you could probably heat the milk/cream, stir in the cocoa powder to dissolve, then chill the mixture before churning it.
If we are talking about something like Hershey's (the brand I know) unsweetened cocoa powder (the dark reddish-brown very fine powder), it can be mixed with cold milk if you make a paste of it first, and then dilute it to the consistency you want. I.e. start with the powder, pour in the milk bit by bit stirring and "mashing" as you go so as not to let any of the powder float on the milk. This cocoa powder also mixes easily with oil & fat, so that property should help with your ice cream ingredients which probably have some butterfat included.
If your recipe includes only ingredients and no instructions, perhaps that paste technique can help.
I enjoy buying vanilla ice cream and mixing in baking cocoa to taste. You can make it as rich as you want, and it tastes good.