Preheat the oven to 375ºF (190ºC). 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-size bowl, whisk together the flour, baking powder, baking soda and salt until well combined.
In a large bowl, cream the butter, sugar and lemon zest, with an electric mixer, until light and fluffy. Add the eggs one at a time and beat until well incorporated. Add the extracts and beat until combined.
On low speed, mix in the flour mixture in two additions, alternating with half of sour cream after each addition. Mix just until combined. The batter will be thick.
Divide the batter evenly into muffin liners. (If using standard muffin liners, fill 3/4 full.) Bake at 375ºF (190ºC) for 5 minutes. Turn the oven heat down to 350ºF (180ºC) and continue baking the muffins until a toothpick inserted into the centers comes out clean, about 12-16 more minutes. Do not over bake.
Transfer the muffins to a cooling rack to cool completely. Brush icing onto the muffin tops with a small pastry brush.