With an electric mixer, beat butter & sugar together in a large bowl until light & fluffy.
Add eggs one at a time, beating each in well. Beat in zest, lemon juice & vanilla. Blend well then add the sour cream; combine.
Sift in flour, baking powder, baking soda & salt; stir in the poppy seeds & parsnip. Combine it all thoroughly, but don’t overmix. Spoon mixture into 10 paper lined muffin cups.
Bake for 20 minutes or until an inserted skewer comes out clean. Allow to cook for a few minutes in the muffin tray, then transfer to a wire rack to cool completely.
Drizzle
Stir 5 tsp lemon juice with powdered sugar to a runny consistency. Drizzle over the completely cooled muffins.