Urgent! Should I sift the flour before I measure it or measure then sift?

Dorie Greenspan Raspberry Lemon Cupcakes


2 1/4 cups cake flour
1 tablespoon baking powder
1/2 teaspoon salt
1 1/4 cups buttermilk
4 large egg whites
1 1/2 cups sugar
lemon zest from two lemons
1 stick (8 tablespoons) unsalted butter, at room temperature
1 teaspoon pure vanilla extract
1/2 teaspoon pure lemon extract

Getting Ready: Center a rack in the oven to 350 degrees F. Prepare cupcake tins by using liners or spray with non-stick cooking spray

To Make The Cake:
1. Sift together the flour, baking powder and salt.