3/4 cup flour, whisked with 1 1/2 tsp cinnamon and 1/2 teaspoon salt
1/2 cup melted unsalted butter
1/4 cup confectioners sugar + 1/2 tsp cinnamon for dusting the top of the cake
Preheat oven to 325. Line an 8"×8" baking pan with lightly greased foil.
In a small bowl beat the egg whites with 1/4 cup of the sugar and the cream of tarter until stiff peaks form, about five minutes at high speed. Set aside.
In a medium bowl beat together the egg yolks and the remaining sugar until pale yellow and creamy looking.
Blend in the flour mixture. Now, use a whisk to slowly whisk in the warm cream (Don’t use an electric beater. The mixture very soupy and will splatter.), then mix in the butter and then fold in the egg whites.
Pour into the prepared pan and bake at 325 degrees until the top is a nice light golden brown and the top is firm but still jiggles some when shaken, about 30 to 45 minutes.
Let cool in the pan until completely cooled (or refrigerate), then carefully use the foil to lift the whole thing out onto a board to cut into serving sized pieces. Dust with the powdered sugar & cinnamon mixture.