Preheat oven to 375ºF. Line a 12-serving muffin pan with tulip baking liners.* (You can also use standard muffin liners. They hold less batter so you may end up with a couple of extra muffins.)
In a medium bowl, whisk together flour, baking powder, baking soda and salt.
In a large bowl, cream butter, sugar and lemon zest, with an electric mixer, until light and fluffy.
Add eggs one at a time and beat until well combined.
Add extracts and beat until well combined.
On low speed, mix in flour mixture in two additions alternating with half of sour cream after each addition. Mix just until combined. Batter will be thick.
Divide batter evenly into muffin liners. (If using standard muffin liners, fill 3/4 full.)
Bake at 375ºF for 5 minutes. Turn oven heat down to 350ºF and continue baking muffins until toothpick inserted in centers comes out clean, about 12-16 more minutes. Do not over bake.
Transfer muffins to a cooling rack to cool completely. Brush icing onto muffin tops with a small pastry brush.
Icing
Whisk icing powdered sugar, melted butter, and 1 tablespoon lemon juice together until smooth. Add additional lemon juice until desired consistency is reached.