Add milk to the blender first. This helps the blades catch the ingredients smoothly.
Drop in the frozen banana, protein powder, cocoa powder, peanut butter (if using), seeds, vanilla, salt, and sweetener if needed.
Blend on low to start, then increase to high for 30–45 seconds until completely smooth.
Add ice and blend again for 10–20 seconds until thick and frosty.
Adjust with a splash more milk if it’s too thick.
Taste and tweak: more cocoa for richness, more sweetener if you prefer, or a pinch more salt to sharpen the chocolate.
Pour into a chilled glass or shaker bottle and enjoy right away.