Can you use margarine instead of butter to make muffins?

Yes, margarine can be used instead of butter to make muffins. Margarine is a dairy-free alternative to butter and can generally be used as a 1:1 substitute in baking recipes unless the texture of butter plays a critical role, as is sometimes the case in laminated dough such as croissants. There might be slight difference in taste between muffins made with margarine versus butter, but it generally is not significant.