In a large mixing bowl, combine the cocoa powder, protein powder, and sweetener. Whisk together until well blended and free of clumps.
Pour in the almond milk and vanilla extract. Add the Greek yogurt. Use a hand mixer or a whisk to combine everything thoroughly until you achieve a smooth mixture.
Sample your mixture, and adjust sweetness if needed by adding more sweetener. If you prefer a richer chocolate flavor, you can add an additional tablespoon of cocoa powder.
Once everything is combined, chill the mixture in the refrigerator for about 30 minutes.
Pour the chilled mixture into a shallow container or an ice cream maker. If using a container, cover it tightly and place it in the freezer. Allow it to freeze for at least 4 hours, or until firm.
Once frozen, let the ice cream sit at room temperature for about 5 minutes to soften before scooping. Serve in bowls and top with your favorite toppings.