Add the Greek yogurt, peanut butter, cocoa powder, honey, vanilla, and sea salt to a mixing bowl or blender.
If using protein powder, add it now along with the milk.
Blend or whisk until completely smooth and creamy.
Fold in the chopped peanuts or walnuts.
Transfer the mixture to a freezer-safe container.
Freeze for about 4 hours, stirring vigorously with a fork every hour to help create a creamier texture.
Let the frozen yogurt sit at room temperature for 5–10 minutes before scooping.
Top with additional chopped peanuts, cacao nibs, shaved dark chocolate, or a drizzle of melted peanut butter if desired.
