Special equipment: two 12-mold madeleine pans (24 molds total) or mini- or regular-muffin pans
Preheat the oven to 350 degrees F. Spray two 12-mold madeleine pans with nonstick cooking spray and set aside.
In the bowl of a standing mixer fitted with the whisk attachment, cream together the eggs and granulated sugar on high speed until the mixture thickens and develops a light pale color, 3 to 4 minutes.
Beat in the almond extract, lemon zest if using, flour, almond meal, salt and baking powder. Turn the mixer down to low speed and slowly pour in the melted butter. Mix until everything is incorporated, but don't over mix.
Divide the batter evenly between the molds in the prepared pans. Bake until lightly golden around the edges, about 8 minutes.
Let the madeleines cool for about 2 minutes in the pan, and then invert them onto a cooling rack to cool completely. Dust with confectioners' sugar if desired.
You'll need a madeleine pan to make true madeleines, but you can also use a mini muffin pan or regular sized muffin pan to bake these; you'll still have a delicious treat. Baking times might be longer or shorter depending on the size of the muffin cups, so keep an eye on them.