A stand mixer is helpful if the batch is a big size, but certainly for 1 to 2-egg-size mixes, by hand with a spoon or with a handheld mixer works well.
It is more critically important to bring your ingredients to room temperature if mixing completely by hand, or it will be very difficult to incorporate the egg into the butter. If your butter and eggs are room temperature, it is easy to cream them by hand in a bowl. A wooden spoon is probably the easiest to get the butter soft and fluffy with the sugar. If you whisk your egg and add it in slowly, that works fine, but if it starts to look wet or clumpy (a broken emulsion), then beat the mixture a bit longer before adding more egg to allow it to incorporate better.
A handheld mixer also works fine if that's what you have. Some people might not like vigorously mixing with a wooden spoon and would therefore prefer a handheld mixer.
From Chef Kathryn
Submitted by aday on January 29, 2021 2:41pm
A stand mixer is helpful if the batch is a big size, but certainly for 1 to 2-egg-size mixes, by hand with a spoon or with a handheld mixer works well.
It is more critically important to bring your ingredients to room temperature if mixing completely by hand, or it will be very difficult to incorporate the egg into the butter. If your butter and eggs are room temperature, it is easy to cream them by hand in a bowl. A wooden spoon is probably the easiest to get the butter soft and fluffy with the sugar. If you whisk your egg and add it in slowly, that works fine, but if it starts to look wet or clumpy (a broken emulsion), then beat the mixture a bit longer before adding more egg to allow it to incorporate better.
A handheld mixer also works fine if that's what you have. Some people might not like vigorously mixing with a wooden spoon and would therefore prefer a handheld mixer.