Chocolate Sheet Cake with Nutella Swirl and Tahini Buttercream

A chocolate sheet cake with a creamy and luscious tahini buttercream

Improv Session

It’s just how it is. There are moments when you have absolutely nothing fresh on the fridge. Those are the moment when you get creative with every bottle or jar you have around, looking like a total witch creating a secret potion. By experience of mixing whatever jars crosses my path, not of looking like a witch, I’ve learned that two things come out of this situation; crazy combinations or delicious classics. But I think this chocolate sheet cake with nutella swirl and tahini buttercream manages to be the best of both scenarios.

I wanted to bake a chocolate sheet cake with a nutella swirl on top but usually cakes with a thick swirl on the batter have only a light glaze on top. Or nothing at all. But then again, I was prowling around the kitchen, wanting to use all the jars I have, when suddenly a tahini jar popped out of the pantry. Bingo! A tahini buttercream will do beautifully on top on that cake. Good things happen when you have a well-stocked pantry!

Even if this is a chocolate cake it turned out super light in terms of flavor because I didn’t use cocoa powder but melted chocolate chips. The crumb has a delicate chocolate note, different from stronger chocolate flavored cakes made with cocoa powder. The tahini buttercream gave this cake a nutty note that I enhanced by sprinkling roasted sesame seeds on top. Those little seeds gave so much texture to this silky cake without being too invasive. And the proportion of the buttercream is almost one to one in relation to the cake, because I imagined this cake having a mouthful bite.

Let me tell you, this cake flew in just a few days. It was impossible to eat just a square. I think the frosting was the best part to tell you the truth. You have to find out for yourself and make this one. IT. WAS. SO. GOOD.

Recipe notes:

1.     Sifting the flour is key here.

2.     If you prefer you can leave the nutella completely out, but it adds another creamy texture to the cake.

3.     Have the tahini well mixed before adding it to the butter.

4.     Sprinkling sesame seeds on top is totally optional. If you want to use them I strongly recommend you toasting them to get that nutty warm notes.

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Chocolate Sheet Cake with Nutella Swirl and Tahini Buttercream


Unbleached all purpose flour – 3 cups, sifted
Baking powder – 4 Tsp
Chocolate chips – 1 cup
Hot water - 1 cup
Instant coffee granules – 1 Tsp
Butter, at room temperature – 8 TBSP
Raw sugar – 2 ¾ cups
Egg, at room temperature - 3
Vanilla extract – 3 Tsp
Fine sea salt – 1 Tsp
Ground cinnamon (optional) – ¼ Tsp
Vegetable oil – 2 TBSP
Coconut milk - 1 cup
Nutella – about 10 TBSP

Tahini Buttercream

Butter, at room temperature but still slightly chill – 1 cup (2 sticks)
Confectioner’s sugar, sifted – 4 cups
Tahini paste, mixed – ½ cup
Vanilla extract – 1 Tsp
Coconut milk – 2 to 3 TBSP

Toasted Sesame Seeds

Raw sesame seeds – 2 TBSP
Pinch of sugar

For a 9” x 13” cake
Total time - 1 hour 15 minutes Active time - 25 minutes
Equipment - 9” x 13” baking pan, stand mixer or hand electric mixer, large bowls

To make the cake: Preheat oven to 350°. Grease with butter an 9” x 13” cake pan. Alternatively you may spray the pan with baking spray or just cover the inside with parchment a medium bowl sift the flour and baking powder.

In a small glass bowl or in a large measuring cup combine the hot water with the chocolate chips and mix until melted. If needed, heat the mixture in the microwave in 10-second intervals until the chocolate is completely melted. Stir in the coffee granules and stir to dissolve. Set aside.

Place the butter in the bowl of a stand mixer or in a large glass or metal bowl. Beat in medium speed for 30 seconds, then add the sugar and beat until butter is fluffier and creamier, about 3 minutes. Add the eggs, one at a time and waiting for one to incorporate before adding the next one. Add the vanilla, salt, cinnamon and oil. Slowly add the chocolate and coffee mixture and beat until incorporated. Decrease the mixer speed and add about ⅓ of the flour mixture and mix just until barely incorporated. Add half of the coconut milk, then repeat these steps, ending with the last ⅓ of flour.

Pour batter over prepared pan. Spoon the Nutella through the top of the batter and with a chopstick or toothpick make some swirls. Bake for 40 to 45 minutes, until a toothpick comes out with a dry crumb when you insert it through the center. Take out of the oven and let it cool down completely before frosting it.

To make the buttercream: Place butter in the bowl of a stand mixer with the paddle attachment or in a large bowl using an electric hand mixer and beat it in medium low speed (#2 in the Kitchen Aid) and beat until the butter is creamier and fluffier, about 2 to 3 minutes.

Add the tahini paste and beat 30 seconds more, until incorporated. Slowly add most of the sugar, leaving about 1 cup out. Add the vanilla and the coconut milk and mix for about 30 seconds. Stop if necessary to scrap down the walls of the bowl and continue beating. Add the rest of the sugar and beat until the frosting is smooth and creamy, about two minutes.

Stop mixer and with a spatula spread frosting on top of the cake, using a big spoon to create swirls or a fork to create ripples. Sprinkle some toasted sesame on top if desire.

To toast the sesame seeds: Place seeds on a medium or large stainless steel skillet and sprinkle the sugar on top.  Heat over medium high heat for a few minutes, until the seeds are golden brown and fragrant, moving them a few times to prevent burning on one side.