I'm in a cookie state of mind, it seems, so this post is sort of Part Two of last week's.
To make a true madeleine, you must have the right pans. I do, thanks to a trip to France many, many years ago (they're a bit bent because I had to stuff them in my suitcase). The finished product is shaped like an elongated shell—a reference to medieval French pilgrimages? Or, as Julia suggests, maybe some early cook tried baking them in a bunch of handy scallop shells—which she claimed worked. If you don't have the pans, use any pans with shallow molds (muffin tins will do) and call them Lemon Tea Cakes.
4 large eggs, at room temperature
2/3 cup sugar
2 tsp vanilla extract
Grated rind of one lemon
4 oz. (1 stick) unsalted butter
2/3 cup all-purpose flour
1/3 cup bleached cake flour
A pinch of salt
Preheat the oven to 375 degrees. Paint the Madeleine molds with melted butter (mop up any that pools in the bottom)
In the bowl of a stand mixer, break the eggs. On slow speed, gradually add the sugar, then the vanilla and the lemon rind. Turn the speed to high and beat for five minutes, until the mixture has doubled in volume (it should look like mayonnaise).
Spoon the batter into the buttered molds, about 3/4 full. Bake 10-12 minutes, or until golden brown. Remove from the molds immediately and let the madeleines cool on a wire rack. They're best eaten fresh (they get a little gooey if they sit).
If you want to emulate Proust, dip your madeleine first into a tisane de tilleul, which, if memory serves, in tea brewed from linden leaves.