I can’t remember the last time I made a layer cake with icing. Maybe never. I prefer to leave these things to the experts. Cakes are not a cakewalk. Especially not in Santa Fe, at 7,000 feet above sea level. So when called upon to bake one for a dinner party, I refused at first.
I was happy to cook anything on the stovetop, but I wasn’t going near the oven. At which point, my friend Sarah revealed a book that got me over the fear: Pie in the Sky, by Susan G. Purdy.
Purdy realized that all the rules of thumb she’d found for baking at high altitude were inconsistent at best. In the mountains, evaporation happens faster, and leavening of any kind is more effective because of the lower air pressure. So, for example, to make a cake you have to increase your oven temperature so that your cake’s structure will “set” earlier, before the cake overexpands or dries out. But a temperature adjustment isn’t enough. You still need to decrease the amount of leavening. You also need more liquid to keep the cake from drying out. But now that you’ve added more liquid, if you don’t add extra flour your cake won’t be able to hold its structure and will fall. It’s a multivariate problem, so the exact adjustments are elusive and have made high altitude baking a real pain in the ass, until now anyway.
Purdy gathered a hundred of her favorite recipes for baked goods and traveled from her home at sea level to test kitchens in four locations: Boone, NC (3,000 feet), Denver, CO (5,000 feet), Santa Fe (7,000 feet), and Breckenridge, CO (10,000 feet). At each place, she iteratively adjusted every recipe until they came out right.
So the resulting book is like five cookbooks in one. The ingredients list for each recipe in the book is a grid, with a column for each altitude. Made in Santa Fe, the 7,000 foot version was fantastic. One of the better cakes I’ve ever tasted, and definitely the best cake I’ve ever made. So here’s the recipe:
You’ll need two 9-inch cake pans, parchment paper, and a mixer.
1. Get your eggs and butter out if you haven’t already, get the oven warming up with the rack in the correct place, and butter the bottom and sides of each pan thoroughly. Line the bottoms of the each pan with a circle of parchment paper and add a second layer of butter on top of the parchment paper.
2. Chop the chocolate and melt it in the microwave on high: 30 seconds; stir; 15 seconds; stir; repeat in 15 second increments, stirring each time until the chocolate has just melted. Set aside.
3. Mix together, then sift the flour, baking soda, salt, and nutmeg in a medium bowl and set aside. Sifting is super important, don’t skip this!
4. Now, let’s get the batter going. In the work bowl of an stand mixer, cream together the butter and sugar until well blended. Scrape down the bowl and add the vanilla and the eggs, two at a time. Mix well to blend, then scrape down the bowl again.
5. Turn the mixer back on, on the lowest speed. Add 1/3 of the flour, then 1/3 of the buttermilk, alternately, until everything has been combined.
6. Fold in the chocolate and stir until well combined.
7. Divide the batter into the two pans, and smooth the top. Bake for the appropriate time for your altitude. The cake should be springy, and a cake tester should come out clean. Just barely. If it’s not done after the minimum time, you’ll be surprised by what two extra minutes in the oven will do.
8. Set the pans on wire racks and let cool for 10-15 minutes, then run a knife around the edge of each cake layer to release them, and invert the cake. Remove the parchment and let the layers cool completely on the wire racks before icing.
For frosting, melt 8 oz of 70+% chocolate in the microwave, combine with 1 cup heavy cream, and put it in the fridge for 30 minutes or so. You’re basically making a ganache. Mix with an electric mixer until you’ve reached a good icing consistency; you may add more cream if you need to thin it out. Ice the cakes, and serve!