Supersoft and moist hazelnut butter cake made with freshly toasted and ground hazelnuts. This hazelnut cake is frosted with a hazelnut penuche frosting, a brown sugar frosting mixed with freshly ground hazelnut paste giving it absolutely excellent flavor.
This might be one of the best cakes I’ve ever made. Hazelnut lovers, THIS IS FOR YOU. I don’t know which I like better: the cake or the frosting? I want both on everything. The nuttiness of the hazelnuts comes through very prominently, the texture of the cake is so so soft and moist, but it’s the flavor that really makes it stand out. Incomparable.
Hazelnuts: Blanched hazelnuts are really best for making hazelnut butter. If you absolutely can’t find them, use raw and unblanched but try to get the skin off right after toasting so you don’t have too many skin bits in the butter.
Brown sugar: I used light brown sugar but dark should be fine too. Don’t substitute with turbinado (it’s not moist enough) or organic brown sugar (ditto).
Cake Flour: Cake flour has a finer mill and added cornstarch which gives this cake its extra tender crumb. If you can’t find it, sub 1 tablespoon of the flour for 1 tablespoon of cornstarch or tapioca starch.
Buttermilk: The tang and cream of buttermilk do wonderful things to make this cake have an incredibly tender crumb. You may sub with kefir (plain) or with a watered down yogurt.
Salt & Vanilla: Fine sea salt (halve the amount if you are using table salt) and pure vanilla.
Canola oil: any basic and flavorless oil will do. Have access to hazelnut oil? Use that! Otherwise I’d stick to something that won’t take away the flavor of the cake.
This is more time consuming (and slightly annoying) than hard.
First you’ll toast the nuts – this brings out their flavor but also prepares them for grinding.
Grinding the nuts into a paste takes patience and some fussing over the food processor; as the nuts grind they’ll start to release their oils. You’ll need to keep opening the food processor and scraping down the sides and packing it into the bottom to get them to grind evenly.
Just keep doing this for 5-7 minutes, you’ll see it turn from bits of powdery nuts, then it will thicken into a chunk which is mostly ground nuts but has enough ‘paste’ to hold it together.
But keep going! Once you see it starting to turn loose and liquid it’s getting close. Keep going and processing on high until it’s like a really thin, runny soup. The video below will show you the consistency needed.
You can store this in the fridge, it’ll keep for a few weeks.
Baking this cake is a fairly simple process, it’s all in a bowl, just use a whisk or a hand mixer.
Whisk the eggs and sugar: whisk until you have a very light, smooth texture. It’ll look like melted ice cream, thick and light, oozing off the spoon.
Emulsify the oil then the nut butter: You’ll add the oil slowly, while mixing, so that it can emulsify into the sugar and eggs. Then do hazelnut butter the same way.
Sift in the dry ingredients: Once it’s all sifted in, stir the batter and while you’re doing so pour in the buttermilk and stir until you have a very smooth but runny batter. Don’t worry about thickness, this looks like soup now but it’ll turn into a cake soon enough.
Careful to whisk just the right amount and bake until the center springs back or a toothpick comes out clean.
This is one of those cake toppings that is so basic and homey, it’ll remind you of your grandmas bakes from back in the day. The first time I came across it was after I saw the deep caves on this banana cake. To me it’s a lot like making fudge: you cook butter and sugar together, then add milk and powdered sugar.
While hot, the consistency is very loose, like a thick soup. As it cools though it settles into a firm but soft layer. The texture is somewhere between a glaze and a buttercream.
I’m obsessed with turning penuche frostings nut- based, if you are a newsletter subscriber you’ve come across these banana cinnamon rolls with a peanut butter penuche, and I’m bound to have that pb penuche on some brownies or cake sometime before this year clocks out.
Cooking penuche: It’s important not to over or under cook the sugar and butter, once the butter is melted, pour the sugar in and whisk. Then leave it to cook for exactly 2 minutes on medium heat. The brown sugar will have dissolved and it’ll look shiny.
Whisking penuche: Make sure this is well sifted! This is going to be your excuse for skipping arm day at the gym. Getting that powdered sugar to dissolve fully into the hot base is going to take quite a bit of strength and vigorous whisking. Keep at it until it’s smooth!
For this hazelnut based penuche frosting we’re going to make a basic brown sugar penuche: melt the butter then cook it with the sugar, once it’s boiled for a few minutes we’ll add milk.
But before we move on to adding the powdered sugar, we’ll add some more of that wonderful hazelnut butter we made, stir well along with some salt and vanilla, then get vigorous and stir in the powdered sugar.
I will say, penuche is SWEET. If you don’t have a sweet tooth you might not enjoy it as much. In this case I’d have the cake as is or top with a thin layer of glaze.
This keeps great at room temperature. The edges where exposed will dry out a bit but I’d hesitate to keep it in an airtight container because the penuche might get overly soft and messy.
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