Make the Cake: Preheat the oven to 350°F. Place the oven rack in the center position. Butter and line with parchment paper 2 (13- by 9-inch) sheet pans or baking dishes.
Set aside the 6 roasted hazelnuts for garnish. In a food processor, combine the remaining 6-1/2 ounces chilled roasted hazelnuts with the powdered sugar, espresso, tapioca starch, and kosher salt and grind until very fine, scraping the corners to prevent nut butter from forming. Set aside.
In a scrupulously clean bowl, whip the egg whites with a whisk, by hand, or in the bowl of a stand mixer fitted with the whisk attachment, on very low speed, until very foamy. With the mixer running, add the cream of tartar. When the whites become opaque, increase the speed to medium, then slowly add the superfine or granulated sugar in a steady stream, taking a full minute to add it all. (It’s important not to add too much too soon, or it will weigh down the whites and prevent them from attaining maximum volume.) Increase the speed to medium-high and mix until stiff, glossy peaks form (lift the beater from the egg whites; the peaks will be pointy when ready).
Scrape the mixture into a large bowl for easier folding. Sprinkle 1/3 of the hazelnut mixture over the egg whites in one layer, then gently fold that in. Repeat for a total of 3 additions and folds. Do not completely incorporate each addition before adding the next; your batter should be hom*ogenous only after the last addition.
Divide the batter between the two pans and spread evenly in each pan. Bake until the cakes are golden and dry to the touch, 20 to 22 minutes.
Place 2 sheets of parchment paper, each slightly larger than the baking pans, on a clean surface. Immediately go around the edges of the cakes with a knife to loosen them from the pans, then invert the cakes onto the parchment paper sheets. Remove the first pan, then very carefully peel off the parchment paper while the cake is still hot. (It’s very difficult to remove when the cakes are cool.) Repeat with the second pan. Let the cakes cool without moving them.
Make the Frosting: Split the half vanilla bean lengthwise. With your hands, use 1 tablespoon of the sugar to exfoliate every bit of vanilla seed from inside the pod. Put the vanilla bean pod, seeds combined with the 1 tablespoon sugar, and the milk in a small saucepan over medium heat and heat to just before the boiling point. Remove from the heat, cover, and let steep for 1 hour.
In the bowl of a stand mixer fitted with the whip attachment, whip the yolks and salt with the remaining 1/4 cup sugar on high speed, until the mixture is light, thick, and makes a ribbon when you lift the whip, about 5 minutes.
Reheat the vanilla milk to hot but not simmering.
With the mixer on the lowest speed, carefully stream the hot milk into the yolk mixture, mixing until combined. Scrape this custard mixture into a saucepan. Clean the mixing bowl. Cook the custard on medium-low heat, whisking constantly, scraping the bottom and the corners of the saucepan as you go, until the mixture just begins to bubble. When the first bubble appears, remove from the heat and keep whisking to ensure even cooking, then pass the cooked custard through a fine mesh strainer into the clean mixing bowl. Whip on high speed until completely cooled, thick, and mousse-like, stopping the mixer to scrape down the bowl, if necessary, about 8 minutes. Scrape into a small bowl.
Switch to the paddle attachment and beat the butter on medium speed, until it’s light, creamy, and completely white, about 6 minutes. Reduce the speed to low, and gradually pour in the custard, incorporating each addition before adding more, until it’s completely incorporated, fluffy, and smooth. If you add the custard too quickly, the buttercream may curdle, but just keep paddling to bring it back together before adding more.
Build the cake: Set aside 2 tablespoons of the Vanilla Buttercream.
Place the almonds in a small skillet over medium heat and toast, shaking the pan continuously, until lightly golden, about 4 minutes. Transfer to a bowl and set aside.
Turn the cake layers upright (remember they'be been cooling inverted). Divide the remaining buttercream equally between the two cake layers and spread a very even layer of buttercream to the edge of each top.
Using a chef’s knife, carefully slice each layer into 3 equal portions, widthwise. Carefully stack the portions on top of each other, lining up all the cut sides together (so you’ll have less to trim later) and reserving the prettiest slice for the top. Chill until firm, at least 1 hour.
Trim the 2 short sides of the cake to cleanly show the layers. Slice the cake widthwise into 6 equal portions. Garnish each with 1 whole hazelnut. Push the slices back together in a neat row and spread the reserved buttercream along the short sides of the slices (the long side of the whole cake).
Using a small offset spatula or a butter knife, carefully separate each slice. Using your hands, dip the frosted shorter sides of each slice into the toasted almonds.
Lightly dust the tops with cocoa powder, if desired. Let the cake come to a cool room temperature and serve with a generous dollop of very lightly sweetened whipped cream.
FAQs
How do you keep gluten free cakes moist? ›
- Add some almond flour: Using a small amount of almond flour in your baking can enhance the taste and texture dramatically. ...
- Add more fat or liquid: It might just be that you need a bit more moisture in your recipe, especially if you're converting a regular “gluten-ful” recipe to gluten-free.
YOUR CAKE IS SINKING IN THE MIDDLE OR NOT RISING
You may not have used enough raising agents. I do recommend experimenting with double action baking powders. Otherwise try using 25 percent more chemical raising agents (baking soda or baking powder) if you're converting a recipe to gluten free.
Gluten-free baked goods often benefit from extra liquid to hydrate the flour blends, eliminate grittiness, and achieve a less dense or dry texture. However, it's very important to drive off this extra moisture during baking, or you'll wind up with a gummy texture.
Why does gluten free cake taste different? ›Flavor Differences
All gluten-free flours have a different taste. Some gluten-free flours are naturally sweet, some are nutty, while others have a strong flavor. When you're just getting started baking gluten-free, experiment with as many different flours as you can.
Moisture – for some reason gluten-free cakes tend to get a little dry. Any gluten-free cake will dry out super-fast and get hard on the outside if it's not properly refrigerated and covered. I swear by always using buttermilk and adding a little more fat into the batter to compensate for the dryness.
What is the trick to gluten-free baking? ›Gluten-free flours often contain fine starches, so they absorb more liquid than conventional flour. To address this, gluten-free recipes usually call for more liquid and produce looser batters. They may also call for a larger quantity of leavening, like baking powder, to help add volume and lighten the texture.
Why is my gluten-free cake so dense? ›If gluten-free cakes aren't falling apart, they often turn out heavy and unpleasantly dense. That's because gluten creates little pockets of air, so baked goods turn out springy and fluffy; gluten-free flours and grains are lacking this crucial element.
Should I let my gluten-free cake batter rest before baking? ›Let Your Batters & Doughs Rest
We recommend covering your batters and doughs and letting them rest for at least half an hour. Note: This will also help batters become thicker and doughs to firm up.
2 teaspoons of baking powder per cup of gluten-free flour is necessary to ensure proper leavening. Baking soda and buttermilk can be used to leaven instead of baking powder, but 1-1/8 teaspoon of cream of tartar should be added for each 1/2 teaspoon baking soda used.
Why does my gluten-free cake taste bitter? ›Rice Flour & Brown Rice Flour – high in carbohydrates. The main drawback is a tendency to produce a bitter taste, especially if baked goods are kept for any period of time. Will give a slight gritty texture when baked.
Can you over mix gluten-free cake batter? ›
However, you can actually mix a batter containing xanthan and/or guar gum to a point of diminishing returns. You can overwork the gums and end up with a stringy cake batter or rubbery cookie dough. (Having said that, doing this takes some work. Just don't take your aggressions out on a gluten-free cake batter.)
Why is my gluten-free cake batter so thick? ›Two types of gum are typically used in gluten-free baking: xanthan and guar. Both of them functionally do the same job that gluten does — hold the batter together and thicken it. Sometimes you'll see them together in a box of pre-made gluten-free flour or cake mix (or recipe); sometimes they appear separately.
What flour is best for gluten free cake? ›Best Overall: Bob's Red Mill Gluten Free 1-to-1 Baking Flour
This mix, which has all recognizable ingredients (including sweet white rice flour, which is the main ingredient in mochi, a nice light, powdery, starchy flour that doubles as a binder), worked well in all three of our tests.
Most gluten-free cookie and cake recipes use white rice flour as the foundation. I use it in almost every Easy, Tasty, Gluten Free recipe. But all rice flours are not alike!
What is the best gluten-free flour for baking cakes? ›What's the best gluten-free flour for baking? Bob's Red Mill gluten-free 1-to-1 baking mix is my favorite gluten-free all-purpose flour blend for baking. It has a mild texture and plenty of "stick" thanks to a blend of sweet rice flour, brown rice flour, and sorghum flour, plus some starches and xanthan gum.
How do you keep gluten-free cake from falling apart? ›Xanthan gum (along with other thickeners like guar gum and arrowroot) acts like a binder in gluten-free baked goods to maintain their structure. Without it, there's a good chance that your brownies or muffin will crumble and fall apart.
Why is my gluten-free cake wet? ›Timing is Key
This is because gluten-free treats often look underdone and slightly wet inside after baking. The starches only set and firm up after cooling, so at first glance, you may think more time is needed in the oven.
Simple syrup is a great all-purpose glaze for cakes and fruitcakes, adding moisture and a bit of sweetness. It's also a key element in certain mixed drinks.
How do you store gluten-free cake overnight? ›Gluten-free baked goods can lose moisture and quality quickly. Wrap them tightly and store in the refrigerator or freezer in an airtight container to prevent dryness and staling.