Preheat oven to 350 degrees. 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. NOTE-
Freezing the berries before adding them to the
batter prevents them from sinking to the bottom
and from discoloring the cupcakes. Bake cupcakes
until tester inserted into center comes out clean,
about 23 minutes. Transfer cupcakes to racks;
2 1/4 cups powdered sugar
10 Tbs (1 1/4 sticks) unsalted butter, room
1/2 cup plus 2 Tbs maple sugar
1/2 tsp coarse kosher salt
1 1/4 tsp vanilla extract
4 tsp (or more) whole milk
1 cup chilled fresh blueberries
Fresh mint sprigs (optional)
Combine first five ingredients in medium bowl.
Add 4 teaspoonfuls of milk. Using electric mixer,
beat until well blended and fluffy, adding more
milk by teaspoonfuls if dry (small granules of
maple sugar will still remain), about 4 minutes.
Spread frosting over top of cupcakes.
Garnish cupcakes with chilled berries, and mint
sprigs, if desired. (Can be made 4 hours ahead.
Store in airtight container at room temperature.)