Freeze ripe, peeled bananas ahead of time.
Soften dates in warm water for 10 minutes if firm, then drain.
Add frozen bananas, cocoa powder, cold brew, peppermint extract, softened dates, and plant-based milk to a blender, liquid last.
Blend until thick and smooth, adding a small splash more milk only if needed.
Taste and adjust peppermint extract in small increments if you want a stronger mint flavor.
Transfer to a bowl immediately using a spatula.
Top with crushed candy canes, chocolate chips, or coconut flakes, and serve right away.