Preheat oven to 375 F. Butter and flour the madeleine pans. If
using a non-stick pan, only use cooking spray. Beat the eggs,
salt, and sugar together until thick, 8 minutes. Add the vanilla.
Fold in the flour, rapidly, but gently. Fold in the butter gently.
Quickly spoon the mixture into the madeleine pans, about 3/4 full.
Bake until golden, about 8-10 minutes. Watch carefully. Remove
from pans, cool on racks. If desired, dust with powdered sugar
after baking.