Peanut Butter Muffins are a popular and interesting variation of the plain muffins made using peanut butter, preferably the creamy type, and such other ingredients like flour, baking powder, eggs, milk, butter, salt and sugar. When made, peanut butter muffins leave a light, spongy and moist feel, and hence are wonderful and filling to be served for breakfast. Peanut butter muffins are most delicious when eaten warm, with an extra peanut butter topping or served plain.