Blueberry Swiss Roll

Ingredients

• 4 large eggs
• 100 g (1/2 cup) granulated sugar
• 28 g (2 tablespoons) neutral vegetable oil
• 1/2 teaspoon vanilla paste or extract
• 1/8 teaspoon salt
• 90 g (3/4 cup) cake flour*
• 1/2 Tablespoon cornstarch
• 1/2 Tablespoon water
• 1/2 Tablespoon lemon juice
• 125 g (1 cup) fresh or frozen blueberries
• 25 g (2 Tablespoons) granulated sugar
• 1 teaspoon lemon zest
• 1/2 teaspoon vanilla extract
• Pinch of salt
• 140 g (5oz) mascarpone cheese
• 3 tablespoons powdered sugar
• 1 teaspoon vanilla extract
• 300 g (1 1/4 cup) heavy cream
• Fresh blueberries
• Powdered sugar

Instructions

1. 1

   Preheat the oven to 350°F/180°C with a rack...: Preheat the oven to 350°F/180°C with a rack in the center. Grease a jelly roll cake pan with oil or non-stick cooking spray and line the bottom of the pan with a sheet of parchment paper.

2. 2

   Separate the eggs. Place the egg yolks in...: Separate the eggs. Place the egg yolks in a small bowl and set them aside. Add the egg whites to the large stand mixer bowl.

3. 3

   Whisk the egg whites at high speed until...: Whisk the egg whites at high speed until the mixture becomes foamy. Add half the sugar while whisking until the egg whites form medium-stiff peaks. Transfer the whipped egg whites to a clean mixing bowl and set them aside.

4. 4

   Add the egg yolks, remaining sugar, vanilla, oil,...: Add the egg yolks, remaining sugar, vanilla, oil, and salt using the same stand mixer bowl. Whisk the egg yolks on high speed for approximately 4 minutes until they triple in volume and become thick and pale. The light yellow egg mixture should drop thick, flowing ribbons back into the bowl when lifting the beater out of the mixture.

5. 5

   Using a rubber spatula, fold a third of...: Using a rubber spatula, fold a third of the egg whites into the beaten yolk mixture, careful not to deflate the air bubbles in the egg whites. Repeat this process two more times with the remaining egg whites.

6. 6

   Balance a sieve over the bowl of eggs...: Balance a sieve over the bowl of eggs and sieve in roughly half of the flour mixture. Using a gentle folding motion, carefully incorporate the flour mixture into the egg mixture, being cautious not to deflate it too much. Repeat this process once more with the remaining flour.

7. 7

   Pour the thick batter into a prepared pan...: Pour the thick batter into a prepared pan and use an offset spatula or dough scraper to carefully spread the batter out into an even layer on the tray. Bake the sponge for around 10-12 minutes until lightly golden brown on the top and the tip of the cake springs back when gently pressed.

8. 8

   While baking the cake, lay a clean kitchen...: While baking the cake, lay a clean kitchen towel horizontally on a work surface so the long edge is closest to you. Generously dust it with powdered sugar. Once the sponge has finished baking, carefully tip it upside down onto the towel with the long edge closest to you. Carefully peel off the parchment paper.

9. 9

   Dust the cake with more powdered sugar, then...: Dust the cake with more powdered sugar, then starting from the short side, roll the cake and the towel up together into a spiral. Leave it to cool on a rack until it's at room temperature.

10. 10

    Combine cold water, lemon juice, and cornstarch in...: Combine cold water, lemon juice, and cornstarch in a small saucepan. Mix it into a slurry. Add the blueberries, sugar, lemon zest and vanilla, and salt.

11. 11

    Place the saucepan over medium heat and stir...: Place the saucepan over medium heat and stir regularly as the mixture begins to warm up. As the mixture boils, it will thicken, become jelly-like, and lose its cloudy appearance. Let it boil for around 2 minutes, stirring continuously before removing the heat.

12. 12

    Tip it into a bowl and let it...: Tip it into a bowl and let it cool to room temperature, then store it in the refrigerator until needed.

13. 13

    Combine the mascarpone, powdered sugar, and vanilla extract...: Combine the mascarpone, powdered sugar, and vanilla extract in a medium bowl. Use a hand or stand mixer with a paddle attachment, starting on low speed, to mix until everything is combined.

14. 14

    Slowly increase the speed to medium and gradually...: Slowly increase the speed to medium and gradually pour in the heavy cream while continuing to whisk until the mixture becomes thick and holds stiff peaks, but don't overbeat it.

15. 15

    On a clean work surface, carefully unroll the...: On a clean work surface, carefully unroll the cooled cake. Spread over 3/4 of the mascarpone cream mixture and use an offset spatula to spread it out, leaving a ½ inch border on all sides. Keep the remaining mascarpone cream for the topping.

16. 16

    Dollop over the cooled blueberry filling, then spread...: Dollop over the cooled blueberry filling, then spread it over the cream with an offset spatula.

17. 17

    Carefully re-roll the blueberry cake roll, without the...: Carefully re-roll the blueberry cake roll, without the tea towel, back into a spiral.

18. 18

    Now gently wrap the towel around the rolled...: Now gently wrap the towel around the rolled cake and let it chill in the refrigerator for 30-60 minutes.

19. 19

    Remove the cake from the refrigerator and cut...: Remove the cake from the refrigerator and cut off the ends of the roll with a serrated knife (about ¼ inch of each end) to neaten them up. Scoop the remaining mascarpone cream into a piping bag and pipe dollops on top of the cake.

20. 20

    Press in some fresh blueberries, then dust with...: Press in some fresh blueberries, then dust with powdered sugar.