Preheat oven to 350°F. Line 12-cup muffin tin with paper liners and set aside.

Whisk together flour and powdered sugar in medium bowl.

Beat egg whites and salt in separate large bowl with electric mixer on high speed until frothy. Add lemon juice and beat until soft peaks form. Gradually add granulated sugar to bowl, a little at a time, beating until stiff peaks form. Fold in flour mixture to egg mixture, about 1/4 cup at a time, with a rubber spatula. Stir in 1 tsp. vanilla.

Divide batter evenly into prepared muffin tin. Bake 18 - 20 minutes, or until tops of cupcakes are lightly browned. Remove cupcakes from pan and let cool completely on a wire rack.

To make the frosting, beat cream cheese with an electric mixer on high speed until light and fluffy. Add yogurt, blood orange juice and 1 tsp. vanilla and beat until smooth and creamy. Pipe or spread the frosting onto each cooled cupcake.