Pour hot water into a bowl. Float another bowl in it to gradually melt the butter. The melted butter should be lukewarm when combined.
Beat the egg in a bowl. Be sure to bring the egg to room temperature beforehand. Add the sugar and mix thoroughly. Dissolve the sugar but be sure not to create any foam.
Add the grated lemon zest and honey. Make sure not to use zest with any waxy or chemical coating. Combine the egg mixture well.
Add the baking powder to the cake flour and stir to combine. Then, sieve the flour into a bowl. Add the flour to the egg mixture. Gradually mix it from the center to the outside. This will help to avoid any pockets of dry flour.
Add the lukewarm melted butter to the mixture a little at a time. Avoid using hot butter otherwise the baking powder will activate.
Let the batter sit at room temperature for about 30 minutes. If the room is hot, let it sit in the fridge.
We are using the aluminum foil cupcake molds for the madeleines. Thin molds easily fall or open so place in other molds to hold them steady. You can also use thick molds or a traditional madeleine pan instead.
Place the batter into each mold. If you make lots of madeleines, consider using a pastry bag to fill the molds quickly. We recommend using a kitchen scale to measure equal amounts of the batter. This will help each madeleine to brown evenly.
Preheat the oven to 180°C (356°F) and bake at 170°C (338°F) for 15 to 16 minutes.
Remove the baking sheet and place it onto a trivet. With the aluminum mold still attached, place the madeleines onto a cooling rack and let them sit to cool.
Be sure to bring the egg to room temperature before use.
If your honey is too firm, lightly microwave to help it mix with the egg mixture.