Here's a tip over 60,000 people have saved to their Pinterest boards:
That's so easy! Especially when you consider how Alice Medrich recommends you soften butter: Repeatedly whack an unwrapped stick, sandwiched between two pieces of plastic wrap, with a rolling pin to flatten it out, then flip, knead, halve, roll, rest, and continue whacking. (So maybe it's a technique more in line with anger management than kitchen "hacks.")
As someone constantly in need of room temperature butter (and constantly without the foresight to take a stick out of the fridge ahead of time), I tested the "tried and true..." method for "softy soft" butter.
I filled a glass with nearly-boiling water, poured the hot liquid out, and immediately turned it over onto a vertical stick of wrapped butter that had come straight from the fridge. The glass retains the heat of the water, creating a cloche (look! a DIY cloche!) in which the butter can warm up.
After a couple of minutes, the butter was still cold-ish. After "a few minutes" (as the tip suggests), it was a little softer on the outside, though still firm towards the center—pliable, yes, but definitely not ready to be creamed in a stand mixer (let alone by hand).
I do think the method would work if you were willing to rewarm the glass every five or so minutes (by refilling—then re-emptying—the boiling-hot water), but I fear that the outside of the butter would soften too quickly in relation to the inside, leaving some near-melty, some still-chilled sections. But as written? The tip just doesn't work very well.
(Update! Editor Amanda Sims has had success using thicker glass, like Pyrex, and microwaving water inside the glass—so that the material gets hot, through and through.)
Seems like Alice's technique—where the butter is smashed into an even layer so that it comes to room temperature at a uniform rate—isn't so crazy after all...
(And if you want soft butter for spreading on toast rather than for baking, it just may be time for a butter keeper.)
Have you come across a popular internet cooking tip that just doesn't work? We want to hear about it in the comments!