Perfect financiers should have a crisp, eggshell-like exterior and moist, slightly chewy interior. Avoid overmixing the batter once you add the brown butter. Fill molds only 3/4 full to prevent overflow. Bake until golden brown and the centers spring back when lightly touched. Overbaking creates dry, tough financiers. The shallow rectangular shape ensures even baking. Cool completely before unmolding and decorating to prevent cracking or breaking.