Preheat oven to 350 degrees F. Place paper liners into cups of a 12-cup standard-sized muffin tin.
In a large bowl, with an electric mixer, combine all muffin ingredients and mix until well blended. Fill muffin cups 3/4 full.
Bake for 15 to 20 minutes, or until toothpick inserted in center comes out clean. Cool 15 minutes. Remove from pan. Let cool completely.
For the Glaze:
Melt butter in a small saucepan. Remove from heat. Whisk in powdered sugar and vanilla. Add milk, a little at a time, to achieve desired consistency. Glaze muffins with desired method (I used a squeeze bottle to decorate mine), or invert tops of muffins into glaze. Place on a flat surface and refrigerate to allow glaze to set.