To make this cake you'll need a 10-inch (16 cup) tube pan.Eggs should be at room temperature before adding them to this recipe. Cold eggs will separate easier than warm eggs, so separate them while still chilled and allow the yolks and whites to come to temperature in separate bowls.
Place the oven’s baking rack on the lowest rung. Preheat oven to 325°F.
Make the cake: In a small microwave-safe bowl, heat the red wine for 45 seconds to 1 minute at full power until hot. Add the baking cocoa and stir until combined; let cool.
In a large bowl, combine flour, sugar, baking soda and salt. In a separate bowl, whisk together the egg yolks and oil; add this to the dry ingredients along with the cooled cocoa mixture. Beat until well blended.
In another large bowl (spotlessly clean and grease-free) beat the egg whites and cream of tartar on high speed until stiff peaks form. Fold the egg whites into the chocolate batter mixture using a large rubber spatula - this will take a little while, just keep folding until no streaks of egg white remains in the batter.
Gently spoon the batter into an ungreased 10-inch tube pan. Run a knife through the batter (avoiding the bottom and sides of the pan) to remove any hidden air pockets.
Bake the cake for 55-60 minutes, or until the top springs back when pressed. Remove the pan from the oven and immediately invert the pan. If you’re using an angel food cake pan, it may have legs for this purpose. If your pan does not have legs, insert a bottle into the center of the cake pan and invert the cake (I used the empty wine bottle for this). It may seem like the cake will fall out, but it should not. Let cake cool completely. The inversion will help the cake achieve maximum height.
Run a knife around the sides and center of the tube pan before turning out. Heather’s note: after doing this I vigorously shake the cake pan so that the sides will further release from the pan. After doing this, I turn the cake onto a cake plate; If the cake releases on its own then – GOOD! If it does NOT release on its own, I vigorously shake the pan again and repeat until the cake releases on its own. If you have a two piece pan, removal may be friendlier.
Make the glaze: Place the chocolate, wine and cream in a microwave-safe bowl. Heat at 30 second increments at 100% power until the mixture can be whisked smooth (about 1 minute total heating time). Whisk in the butter and mix until incorporated. Let the mixture stand until thickened, about 10 minutes (speed this process in the refrigerator). Pour the glaze over the cake. Serve immediately.
For best results, store leftovers in an airtight cake keeper.
Keyword chiffon, heavy cream, red wine, semisweet chocolate