Many baking recipes call for softened butter. But I rarely remember to take the butter out of the fridge to soften, and all too often, when I do, I run out of time to bake and end up tossing the butter back in to the fridge. Fortunately, I picked up a little tip from my favorite chocolate chip cookie recipe, which I adapted from Thomas Keller's cookbook Ad Hoc at Home, and this technique works great for all of my baking now:
To quickly soften cold butter for baking, simply cut the cold butter into small pieces, then put the butter in a mixer and beat until creamy.
As you can see in the photo above, I cut the butter lengthwise four times on each side, then slice the butter into half-tablespoons, which creates a cross-section of sixteen small pieces. A stand mixer is great for this method, because you can dump the butter pieces in, start the mixer, and walk away. But a hand-held mixer should work fine too. The process takes anywhere from five to ten minutes, depending on how cold the butter and air in the room are.
This method works a lot better than microwaving butter, which tends to melt the butter rather than softening it.