In a large bowl whip the butter until light and fluffy. Slowly add the powdered sugar until fully incorporated. Mix in the milk, lemon juice and zest. Add a small drop of yellow food coloring to give it a soft color.
Serve frosting piped or dolloped on each cake slice.
Notes
The cake and glaze recipe are included with the bundt pan. The frosting is my recipe.
Recipe by Friday is Cake Night at https://www.fridaycakenight.com/2015/09/lemon-square-bundt-cake/