Ingredients
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2 cups all-purpose flour
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1 tsp baking powder
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1/4 tsp baking soda
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1/2 tsp salt
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1/3 cup sour cream, room temperature
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1/3 cup whole milk
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2 tsp vanilla extract
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1 tsp lemon extract
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1/2 cup unsalted butter, room temperature
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1 cup granulated sugar
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2 large eggs, room temperature
Icing:
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5 cups confectioners' sugar
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Boiling water, as needed
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2 tbsp light corn syrup
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1 tsp vanilla extract
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1/2 tsp salt
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1 tbsp unsweetened cocoa powder
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Blue food coloring, as needed
Steps
1
Preheat oven to 375°F. Line two cookie sheets with parchment. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. In a separate medium bowl, whisk together the sour cream, milk, vanilla extract, and lemon extract.
2
In a large bowl with an electric mixer, beat together the butter and granulated sugar on medium 5 min., until light and fluffy. Beat in the eggs, one at a time, until combined, scraping down sides of bowl. Reduce mixer speed to low. Add flour mixture in 3 additions, alternating with milk mixture. Beat until well combined (batter will be thick).
3
Scoop 1½-tbsp mounds of batter onto prepared baking sheets, 2 inches apart. Bake 12–14 min., rotating sheets halfway through baking. Let cool on wire racks 15 min., then flip flat-side up.
4
Meanwhile, make the icing. To a large bowl, add the confectioners’ sugar. Whisk in 4–5 tbsp boiling water, plus the corn syrup, vanilla, and salt. Continue to whisk, adding more boiling water, 1 tbsp at a time, until icing is thick but spreadable. Divide icing into 2 bowls. Add the blue food coloring to one bowl and stir to combine, leaving the other one white. (You can also divide icing into 3 or 4 bowls. Add 1 tbsp unsweetened cocoa for chocolate icing, or red and green food coloring.)
5
Using the back of a spoon, spread white icing over half of each cookie. Let set, then spread other halves with blue and chocolate icing, if using.
Tips
Use red and green icing for a Christmas spin, if desired.