Preheat Oven & Prepare Pan: Preheat your oven to 350°F (175°C). Grease your Madeline pan with butter or non-stick spray, or lightly flour it to prevent the cookies from sticking.
Mix Wet Ingredients: In a large bowl, whisk together the melted butter and sugar until the mixture is smooth and creamy. Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract and lemon zest (if using).
Combine Dry Ingredients: In a separate bowl, sift together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing gently with a spatula until combined.
Add Heavy Cream: Pour in the heavy cream and gently fold the batter to incorporate it, ensuring a smooth and thick consistency.
Chill the Batter: Cover the batter with plastic wrap and refrigerate for at least 1 hour. Chilling helps the batter firm up, which will give the Madelines their signature shape and texture.
Fill the Pan & Bake: Spoon the chilled batter into each cavity of the Madeline pan, filling them about three-quarters full. Bake in the preheated oven for 10-12 minutes, or until the cookies are golden and a toothpick inserted into the center comes out clean.
Cool & Serve: Remove the cookies from the pan and allow them to cool on a wire rack. Once cool, dust them with powdered sugar if desired, and serve.
