For months, I made 4 doz muffins every morning, kissing up for a job. I'd make up the batter, put it
in the muffin tins and cover it overnight, then bake 'em in the morning. Only thing I'd add in the AM was sanding sugar for the topping. Banana muffins will probably darken a bit but that shouldn't be a problem.
Got my equity card that way.