Cream together the softened butter and sugar until fluffy, about 5 minutes.

Add eggs one at a time, beating between additions.

In a separate bowl, combine flour, baking powder, baking soda and salt. Whisk to thoroughly combine; set aside.

In a 4-cup measuring cup, combine lemon juice, butter milk and vanilla; set aside.

Add the flour mixture and buttermilk mixture alternately to the creamed butter, beating to combine between additions. Begin and end with flour.

Whisk in lemon zest by hand.

Scoop batter into mini muffin tins that have been lined with mini muffin paper liners.

Bake at 350 degrees for about 15 minutes.

Cool completely before icing.

Combine all ingredients into the bowl of a mixer and beat until smooth and fluffy.

Adjust powdered sugar for consistency and taste.

Use immediately or cover and refrigerate until ready to use.

Ice cooled muffins.