Prepare the Ingredients:
Peel the ripe banana and break it into chunks. Measure out the milk, cocoa powder, protein powder, and peanut butter.

Blend Ingredients:
In a blender, combine the banana, milk, cocoa powder, chocolate protein powder, and peanut butter. If you prefer a colder shake, add a handful of ice cubes.

Blend Until Smooth:
Start blending at a low speed to combine the ingredients, then increase to high speed. Blend for about 30-45 seconds, or until the mixture is completely smooth and creamy. Scrape down the sides of the blender if necessary.

Taste and Adjust:
Taste the shake and adjust sweetness if needed. If you want it sweeter, add a drizzle of honey or maple syrup and blend again.

Serve:
Pour the shake into a tall glass. You can also garnish it with a sprinkle of cocoa powder or a slice of banana on the rim for presentation.