about the butter:
- sticks are usually marked in tablespoons, so 4 T = 1/4 cup.
- use butter or oil. oil is easier to use, but won't taste as good. butter tastes great, but you'll have to either melt it or cream it with the sugar, a little bit more of a hassle. an extra bowl or cup to wash if you nuke it.
about the berries:
- if you use canned or frozen and you want the muffins to look nice, rinse them first. using them as-is can make the muffin batter purplish-grey
- you can use frozen berries as they are, but if there's a lot of frost & ice, run them under some water and drain well first.