This is such an elegant and sophisticated cake. The contrast of the sweet cake with the bittersweet chocolate and the bite of the espresso is wonderful, and the texture is somehow softer than a traditional angel food cake. I made it once with the instant espresso, and once with instant coffee. I did crush the coffee crystals in my mortar and pestle so they would have a mimic the texture of the espresso powder. Honestly, I could not tell the difference in the two cakes, so I think the substitution is fine if instant espresso is a challenge to find where you live. Thank you for sharing the wonderful recipe.
I also love chocolate and espresso and compliment PetitFour's sophistication in serving her espresso with a twist of lemon. All these aromas and flavors contribute to a wonderful angel cake. About the freckles, I found that the smaller pieces worked very well but the larger chunks settled to the bottom more like moles. Next time I might use semisweet mini chips or chop my bittersweet more evenly. I'll confess a major substitution: Being short on time, I used an angel cake mix and included 3oz. of freshly brewed espresso in the 1 1/4 cups of water called for on the box. After mixing per directions, I followed this recipe exactly beginning with Step 11. This recipe worked incredible wonders for the cake mix. I look forward to making it again--from scratch when I have the time. Finally, I agree that serving this with a chocolate or fudge sauce is about as good as it gets. I also think this cake would make a great base for a tiramisu. Thank you very much for posting the recipe!!
Be still my heart and all other organs, tis truly delicious, in line with Tommygato's comment I pared some caillebaut dark bitter as thinly as I could and it was wonderful, for some reason not yet explainable to me, I decided to make some creme anglaise to serve with it and it was a major sellout, your cake was such an inspiration, thank you LuluB