Place the frozen banana slices, protein powder, almond milk, and peanut butter into a high-speed blender.

Add ice cubes to the blender jar to achieve a thicker, ice-cream like viscosity.

Process on high speed for 45 to 60 seconds until the base mixture is completely smooth.

Add the chopped walnuts and dark chocolate chips to the blender.

Pulse the blender 3 to 4 times to incorporate the solids without fully pulverizing them to ensure a chunky texture.

Transfer the mixture to a chilled glass and serve immediately with a spoon or wide-diameter straw.