You need a very clean, dry bowl for beating egg whites, so I do that step first. They’ll be fine standing for a few minutes while you prepare the rest of the batter (and you don’t have to worry about cleaning the bowl twice).
1 cup flour
½ cup pistachios, very finely ground
1 ½ teaspoons baking powder
½ teaspoon salt
½ cup milk
½ teaspoon vanilla extract
¼ teaspoon almond extract
2 large egg whites, at room temperature
4 tablespoons butter
½ cup sugar
1. Preheat oven to 350º. Coat a 12-cup muffin tin with cooking spray. In a medium bowl, whisk together the flour, pistachios, baking powder and salt; set aside. Stir extracts into the milk; set aside.
2. Beat the egg whites until stiff but not dry. Carefully transfer to a bowl and set aside.
3. Add the butter and sugar to the mixing bowl; fit mixer with paddle attachment. Beat until mixture is fluffy. On low speed, gradually add flour mixture. Slowly pour in milk-extract combination, and beat until just mixed (at this point, the batter will be very thick – do not over beating or it will create a tough crumb).
4. Fold in the beaten egg whites. Evenly spoon batter into prepared muffin tin. Bake for 13 to 15 minutes, or until a toothpick inserted comes out clean.