The phrase "least hassle" means the option or choice that brings the fewest problems or difficulties. It refers to a situation or task that is easy or requires the least effort. Full definition
We will also provide you with a history report and the best and least hassle free buying experience around. (usedcarsgroup.com)
At least a hassle implies that someone needs something. (lawfirmsuites.com)
The smaller container stores a single serving of 8 ounce which is perfect for quick trips or for times when you want as least hassle as possible — think of them times during the night, when the last thing you want to do is prepare formula or mess around with the large container in the pitch black! (mombible.com)