all purpose flour
2 1/4 cups powdered sugar
10 tablespoons unsalted butter, room temperature
1/2 teaspoon coarse kosher salt
1 1/4 teaspoons vanilla extract
4 teaspoons (or more) whole milk
1 cup chilled fresh blueberries
Fresh mint sprigs (optional)
Preheat oven to 350°F.
Line two 12-cup muffin pans with paper liners.
Sift flour and next 4 ingredients into large bowl.
Whisk melted butter and oil in medium bowl.
Add eggs; whisk to blend.
Whisk in buttermilk, milk, vanilla extract, and peel.
Add buttermilk mixture to dry ingredients; whisk just to blend.
Stir in frozen blueberries.
Divide batter among liners.Bake cupcakes until tester inserted into center comes out clean, about 23 minutes.
Transfer cupcakes to racks; cool.
Combine first 4 ingredients in medium bowl.
Add 4 teaspoons milk.
Using electric mixer, beat until well blended and fluffy, adding more milk by teaspoonfuls if dry, about 4 minutes.
Spread frosting over top of cupcakes.
Garnish cupcakes with chilled berries, and mint sprigs, if desired.