Step 1: Prepare Your Pan - Preheat your oven to 180°C (350°F). Grease your madeleine pan with a bit of butter and dust it lightly with flour.
Step 2: Beat the Eggs and Sugar - In a mixing bowl, combine eggs and sugar. Whisk until pale and fluffy, about 5 minutes.
Step 3: Add Vanilla and Melted Chocolate - Add vanilla extract and melted chocolate. Gently fold in until fully combined.
Step 4: Combine Dry Ingredients - Whisk together flour, baking powder, and salt. Gradually add to egg and chocolate mixture, folding gently.
Step 5: Incorporate Butter - Add room temperature butter and fold in until evenly distributed.
Step 6: Fill the Pan - Fill each mold of the madeleine pan about 2/3 full.
Step 7: Bake - Bake for 10 to 12 minutes, or until edges are golden brown and centers spring back when touched.
Step 8: Cool and Serve - Let cool in the pan for a few minutes, then turn out onto a cooling rack. Dust with powdered sugar before serving.