3 1/4 cups all purpose flour |
1 1/4 cups sugar |
1 tablespoon baking powder |
1/2 teaspoon coarse kosher salt |
1/4 teaspoon baking soda |
6 tablespoons (3/4 stick) unsalted butter, melted |
1/4 cup canola oil |
2 large eggs |
1 cup buttermilk or low-fat yogurt |
1 cup whole milk |
1 teaspoon vanilla extract |
1 teaspoon grated lemon peel |
1 1/4 cups fresh blueberries, frozen for 4 hours |
2 1/4 cups powdered sugar |
10 tablespoons (1 1/4 sticks) unsalted butter, room temperature |
1/2 cup plus 2 tablespoons maple sugar |
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) |