Special equipment: a candy thermometer
For the moon pie cookies
: Preheat the oven to 375 degrees F. Grease
2 large baking sheets.
Melt the butter with the marjoram in a large saucepan on low heat. Remove from the heat and stir in the sugar and salt. Add the egg whites one at a time and stir until well blended after each addition. Stir in the flour.
Drop the batter
by rounded teaspoonfuls 2 inches apart onto the prepared baking sheets. Bake, one baking sheet at a time, until the edges of the cookies are browned (the centers should remain pale), 8 to 10 minutes. Immediately remove the cookies to wire racks to cool completely.
For the marshmallow filling: In a small bowl, soak the gelatin
in 2 cups of cool water to soften.
In a small saucepan fitted with a candy thermometer, mix together the sugar, corn syrup
. (Note that you will use this saucepan
twice, to make the syrup and melt
the gelatin, eliminating the need to wash it between uses.) Place the saucepan over medium-high heat.
Meanwhile, in the bowl of an electric mixer, pour in the egg
whites and beat on low speed until frothy
. Add the pinch of salt. When the sugar syrup
reaches about 210 degrees F, increase the speed of the mixer to high and beat the whites until they are thick and fluffy.
When the syrup reaches 245 degrees F, while the mixer
is running on high speed, slowly pour the hot syrup into the whites, pouring so that the syrup does not fall on the whisk
(or some of the syrup will splatter and stick to the sides of the bowl). Continue mixing.
Scrape the gelatin and 1/3 cup of the soaking water into the pan that you used for the syrup. There should still be enough residual heat left in the pan from making the syrup to dissolve the gelatin.
Pour the liquefied gelatin slowly into the whites as they are whipping. Add the vanilla paste and continue to whip
until the mixture feels completely cool when you touch the outside of the bowl, about 5 minutes.
Immediately pipe the marshmallow
into the cookies and sandwich.