Preheat oven to 350°F and prepare two 8-inch cake pans with butter and parchment rounds.
Sift together the flour, baking powder, salt and cinnamon, set aside.
In a stand mixer whip the eggs until light. Slowly add the sugar and whip until light and fluffy, about 3-5 minutes. Add the hot water and vanilla, beat for another minute. Remove from mixer and gently fold in the sifted flour.
In a clean bowl whip the egg whites until stiff peaks, but don't let them get dry or they will be hard to fold into the batter. Gently fold the egg whites into the cake batter.
Divide evenly (they will not be very deep) into the prepared pans and bake for about 20-25 minutes or until the top is golden brown and a tester comes out clean. Set aside to cool completely.