I love watching madeleines bake, the batter rising with the characteristic little bump, pregnant with flavor. It's important not to overbake madeleines; they must be moist. We found when testing these at home that the best way of preventing them from sticking is to thoroughly butter the mold and then refrigerate or freeze the pan to harden the butter before adding the batter. And if your madeleine mold is very old, consider buying a new nonstick one.
Note: You'll need a 12-mold madeleine pan and a pastry bag with a ½-inch plain tip (optional). To get the classic bubble on the madeleines, baking in a convection oven is preferable.
Place the flour in a medium-sized bowl and sift in the baking powder. Add the salt and whisk together.
Combine the eggs and granulated sugar in the bowl of an electric stand mixer fitted with the whisk attachment, and mix on medium-high speed for about 1 minute, warming the bowl gently as needed to dissolve the sugar. Increase the speed to high and whip until the color lightens and the batter doubles in volume, about 4 minutes.
Meanwhile, heat the butter, brown sugar, and honey in a small saucepan over medium-high heat, whisking to dissolve the sugar, about 1 minute. Remove from the heat.
Remove the bowl from the mixer stand and fold in half of the dry ingredients, then fold in the remaining dry ingredients until just combined. Scrape the bottom of the bowl to incorporate any dry ingredients that may have settled.
Pour the warm butter mixture over the batter, add the lemon oil, if using, and fold until the mixture is incorporated and the batter is smooth. Place the batter in a covered container and refrigerate overnight.
Preheat the oven to 350 degrees.
Brush the madeleine pan with butter. Refrigerate or freeze the pan to harden the butter.
Transfer the batter to the pastry bag, or use a spoon. Pipe or spoon the batter into the molds. Tap the bottom of the pan against the work surface to smooth the top of the batter.
Bake until the tops are browned lightly and a skewer inserted into the center comes out clean, 7-8 minutes in a convection oven, 8-9 minutes in a standard oven. (The bottoms of the madeleines will brown more quickly than the tops, so keep the tops on the lighter side.) Immediately unmold the madeleines and cool on a cooling rack.
The madeleines are best the day they are baked, but they can be stored in a covered container for up to 1 day.