Fancy Hazelnut Jelly Roll Cake

Temperature: 350 F

Bake Time: 15 minutes

Tools: Jelly Roll pan (deep baking sheet), parchment paper, kitchen towel, Stand Mixer or Hand mixer, 4 mixing bowls, a sturdy spatula, Food processor or pestle and mortar, medium heavy-bottomed saucepan, whisk, and ladle (optional, but helpful)

Servings: 6-10, depending on cut size

Total Time: 3 hours to 2 days (approximately 1.5 active hours)

Ingredients:

Hazelnut Diplomat Cream

Pastry Cream:

2 Cups Heavy Cream

⅔ Cups Granulated sugar

3 Large Egg Yolks (save the whites!)

4 Tbsp Cornstarch

5 Tbsp Cocoa-Almond-Hazelnut Spread (or just cocoa-hazelnut spread)

Chantilly Cream:

⅔ Cup Heavy Cream

3 Tbsp Sugar or Maple Syrup

1 Tsp Vanilla Bean paste or Vanilla extract or half of a vanilla bean pod

Hazelnut “Jaconde” Sponge Cake:

⅓ Cup Ground Hazelnuts

⅔ Cup Almond Flour

3 Tbsp All-Purpose Flour

3 Large Eggs

3 Large Egg Whites (the ones saved from the pastry cream yolks!)

½ Cup Granulated Sugar (for whole eggs)

2 Tbsp Granulated Sugar (for egg whites)

⅛ tsp Salt

Recipe:

1. Prep the pastry cream at least 2 hours before baking the rest of the cake (or even the day before), to allow it to cool fully before utilizing.

2. In a medium saucepan, heat the Heavy Cream to scalding, but not to a boil.

3. As the cream heats, whisk the egg yolks and sugar together in a heat-safe bowl. Whisk for a couple minutes (by hand), until the mixture is light yellow in color.

4. Temper the egg yolk mixture with the hot cream by either pouring or ladeling a small amount of cream into the egg yolks and whisking continuously as you very slowly add at least half of the cream to the egg yolks. (adding the hot liquid to the egg yolks can cook the egg and curdle the cream, so go very slowly!)

5. Whisk in the Cornstarch and then pour the tempered egg yolk mixture into the saucepan. Cook on medium heat until it begins to thicken to something close to warm pudding, thickly coating the back of a spoon. Then remove from the heat. Note: it will thicken further as it cools.

6. Pour the thickened custard into the mixing bowl and add the cocoa-almond-hazelnut spread, stirring until the mixture has an even color. Cover the pastry cream with plastic wrap, pushing it to touch the pastry cream so that the cream will not form a skin on the top as it cools. Chill in the refrigerator for at least 2 hours or overnight.

7. Make the cake. Preheat the oven to 350 F (177 C). Prep the jelly roll pan by greasing the pan and placing parchment paper on top of it.

8. Using a stand mixer, add whole eggs and sugar to the bowl and whisk them on high speed for approximately 7-8 minutes. They should become very light yellow in color and very fluffy. The batter will “ribbon” when it is done, meaning that the batter that falls from the whisk attachment does not immediately reabsorb into the batter, but “sits on top”.

9. While the eggs are whipping up, combine the Ground Hazelnuts, Almond Flour, and All-Purpose Flour into a bowl. Once the eggs are fluffy and aerated, gradually and gently fold the flour mixture in, trying to preserve the airiness that the mixer just created, and pour the batter into the mixing bowl.

10. Make the meringue. Add the egg whites to the stand mixer and whisk at low-medium speed until they begin to froth, then gradually add sugar and salt. Whisk until stiff peaks (or points) form when removing the whisk.

11. Gently fold the meringue into the rest of the batter, folding until just combined.

12. Pour the batter into the prepared jelly roll pan and even it out with a spatula.

13. Bake for about 14 minutes (13-15, depending on your oven) at 350 F (177 C). It is very thin, so it can dry out quickly, be sure not to over bake it.

14. Cool the cake in the pan on a wire rack. Cool it completely before assembly.

15. While the cake is cooling, prepare the chantilly cream for the diplomat cream. With the whisk attachment on the stand mixer, add the heavy cream, Syrup or Sugar, and Vanilla and whisk into “whipped cream” consistency (it will hold its shape instead of being liquid).

16. Fold the chantilly cream into the chilled pastry cream until fully integrated and then (optional) place the diplomat cream into a pastry bag, fitted with the tip of your choice.

17. Time to assemble. (this is necessary, I promise!) Take a kitchen towel (a non-fuzzy style towel) and dust it with powdered sugar, the entire surface. Place the towel, sugar side down, onto the cooled sponge cake, pulling it tightly, and then inverting the cake onto the towel (and then back onto the counter).

18. Pipe, or spread (if not using a piping bag or equivalent), the Diplomat Cream onto the sponge cake, covering it from edge to edge, about a quarter of an inch (¼”) thick.

19. Starting at the short end, begin to very gently roll the cake until it resembles a log.

20. Place the jelly roll cake onto a tray or dish and use the remainder of the diplomat cream to decorate the outside of the jelly roll however you choose! I like to make little rosettes, or swirls. Make it as fancy as you’d like!

Refrigerate for up to four days.