Preheat oven to 325 degrees F. Line 12 muffin tins with paper liners (not waxed). Do not grease and do not use non-stick.
In a medium bowl, combine cake flour and baking powder.
In another medium bowl, add the 4 egg whites. Place the egg yolks in a large bowl. Add the salt and cream of tartar to the egg whites. Beat until soft peaks form. Continue beating and slowly add 1/2 of the sugar. Beat until stiff peaks form.
Add the remaining sugar to the egg yolks. Beat until light and pale yellow. Mix in the butter, orange zest, vanilla, and orange extract.
Alternate adding the flour mixture in thirds and the orange juice in halves to the yolks, beginning and ending with the flour. Stir until just incorporated.
Gently fold in the egg whites, in thirds, until just combined. Gently transfer into the prepared muffin tins, about 3/4 full. Bake in preheated oven until golden on top and toothpick inserted in center comes out clean, 30-35 minutes. Remove from pan and let cool on wire rack.
While the cupcakes are cooling, prepare glaze by whisking together orange zest, powdered sugar, and orange juice until smooth. If too thick, add a little more orange juice. If too thin, add more powdered sugar. Drizzle the glaze over completely cooled cupcakes.