Preheat oven to 325. Line the bottom of a roasting pan with a small dish towel. Butter and sugar 8 ramekins and place them on top of the dish towel in the roasting pan.
In a bowl, combine flour, 1/4c sugar, salt and lemon zest. Mix.
In the bowl of a stand mixer, whip egg whites and 1T sugar until they form soft peaks.
Meanwhile, in a small bowl, whisk buttermilk, egg yolks, and lemon juice. Whisk in flour mixture until smooth. Fold in egg whites.
Pour batter evenly into prepared ramekins. Carefully make a water bath by pouring hot water into the roasting pan until the water is halfway up the sides of the ramekins.
Tent the pan loosely with foil. Take caution when placing the pan in the oven, being careful not to spill or splash the water bath. Bake for 20 minutes. Remove foil and bake another 20 minutes or until cakes spring back when touched in the center.
Remove ramekins from water bath and place on a cooling rack. Allow to cool at least 15 minutes. Run a butter knife carefully around the edge of the cake to loosen. Invert onto serving plate. Top with homemade preserves and serve.