There is a lot to be said for choosing food that is healthy to eat. But dessert should not be that. Dessert, to me, is a sacred indulgence, an opportunity to stop thinking about the health value of what you are eating and instead have only one thought: gosh darn, this is delicious.
What I'm saying is: ignore the fact that this almond cake is sort of good for you. Don't make it just because almonds are a great source of protein and healthy fats, just because it's gluten-free, or just because it has no refined sugar. Make it because it tastes so good.
The recipe for this light and tender almond cake is very similar to the classic Galician cake called tarta de Santiago or St. James' cake, which dates back to the Middle Ages. The Spanish version usually calls for refined cane sugar and citrus zest. I love this honey-and-vanilla version, but one of the great things about this recipe is that it is a fantastic blank slate for playing with different flavors. Ground cardamom or other warm spices can be lovely in it, as can some berries added to the bottom of the pan before baking.
The reason this cake bakes up with such a tender crumb, rather than forming a flat, dense pancake, is thanks to the chemistry of egg whites. Which means that beating the eggs whites properly is the key to success here.
Egg whites are about 90% water and 10% protein, with the proteins curled up and floating through the water. As they're agitated, though, the proteins unfurl and form a web, trapping the air and water and making a foam. When you bake that foam (in this case, with the almond flour, honey, and yolks folded in) the heat first causes the air bubbles to expand a little and then the web to set, ultimately yielding that nice, light crumb.
Whipped egg whites can be tricky, though; whip them too hard or too fast and they can become grainy or broken. Sometimes you can whip them forever and it seems like nothing is happening. After years of working as a professional pastry cook, I've learned some tricks that make it a piece of...er...cake.
In addition to this great egg-white-beating slideshow, here are some of the things that help me keep my sanity while whisking egg whites.
1. Use Room-Temperature Egg Whites
I know a baker who is obsessed with macarons—another pastry that depends entirely on perfectly whisked egg whites—and she insists on only using very fresh eggs and leaving the separated egg whites out on top of the fridge overnight to get the optimal performance out of them. I don't think you need to flout food-safety rules like she does to get good results from your egg whites. If you don't have the foresight or the desire to take your eggs out of the fridge a few hours ahead of time, you can just soak the eggs in a hot water bath for about 15 minutes before you need to use them. Back at my first pastry job, the very first thing I did every morning (at 3:30 a.m.) was to fill a big bowl with eggs, then cover them with hot water to temper for the day's cakes.
2. Everything Must Be Impeccably Clean
The egg whites need a completely clean environment to whisk up properly. Any dust, debris, or grease in your mixing bowl, or on the whisk or beaters, can interfere with the formation of the foam. Also, even the tiniest amount of yolk in your egg whites will prevent the foam from properly forming. When you are separating your eggs, crack them into a small bowl and separate them one at a time: if a yolk breaks, set that egg aside for scrambling and continue cracking the remaining eggs into a new clean bowl.
3. Slow and Steady Wins the Race
One of the most helpful things I've learned is to pace oneself when whisking whites. I used to always start off with the mixer on high (get 'em going, right?), but then I'd often end up with broken or grainy foam. Instead, it's better to start off with the mixer on the lowest speed until the whites are foamy, then gradually increase the speed as you go, but I never take mine past about medium speed. The slower you go, the more stable your foam will be in the end. You'll also get more consistent, tight little air bubbles. For this recipe, which calls for the egg whites to be whisked to soft peaks, it takes me about 10 minutes. You really want to keep the foam soft here, since stiff foam makes for a tougher cake with a drier mouth-feel (you're almost making macarons if you go too far). That's one more reason to beat the eggs slowly: It's easier to stop at just the right moment when you aren't doing 100 in a 50 mph zone.
4. Add Acid
The one trick I wish I'd known years ago is to add a few drops of lemon juice once the eggs get foamy. A tiny touch of acid helps the foam form and stabilize significantly. Any acid will do—vinegar or cream of tartar work well—but I always have a lemon handy and I like the flavor, so that's what I use.
One final note about the almonds: I have used store-bought almond flour, blanched (skinned) almonds, and whole (skin-on) almonds to make this cake. If you have a food processor and can grind the almonds into flour yourself, that is the best way to go, since the aroma and flavor are fantastic. I always run my homemade almond flour through my flour sifter to sift out the pebbly pieces, which makes for a more tender cake. (I lightly toast the leftover larger pieces of almond and use them to top ice cream or yogurt.)
The flour ends up having more volume than the nuts you start with, even after sifting out the larger pieces. For instance, for this recipe, I start with 1 1/2 cups of whole almonds to get a final yield of 1 3/4 cups almond flour, plus 1/2 cup of the coarser almond pieces.
As for whether to use whole or blanched almonds, it really depends on your taste. Blanched almonds yield a lightly browned crust and a blond crumb, while whole almonds yield a darker, more rustic cake with a complex, earthier flavor.
This is a favorite of mine to whip up last-minute and take anywhere. And remember, don't think about the fact that it's healthy, just enjoy it for being gosh-darn delicious.