Add softened ice cream and milk to the high-speed blender. Start with less milk for a thicker consistency - you can always add more.
Add broken cookie pieces and any optional ingredients like vanilla extract or natural sweetener. If using fresh strawberries, add them now for a fruity twist.
Blend on medium speed for 15-20 seconds, then increase to high speed for another 10-15 seconds until smooth and creamy. Avoid over-blending to prevent melting.
Check consistency and adjust by adding more milk for thinner texture or more ice cream for thickness. Pulse briefly to incorporate any adjustments.