Salted egg yolk sponge cake

Instructions

1. Step 1

   Preheat the oven to 150°C and line the bottom and sides of a 20 cm square pan with parchment paper. A moderate temperature helps the sponge rise evenly without the top cracking. The oven is ready when it has preheated for a full fifteen minutes and the parchment fits snugly into the corners of the pan.

   Mark step 1 as done

2. Step 2

   Whisk 90 g egg yolks with 15 g granulated sugar and a pinch salt, add 40 g vegetable oil and 50 g whole milk, then sift in 70 g cake flour and stir gently. The oil and milk keep the sponge moist and soft enough to soak up the egg mayonnaise. The mixture is ready when it is golden, smooth and falls from the whisk in an even ribbon.

   Mark step 2 as done

3. Step 3

   Use a mixer to whip 160 g egg whites with 1 g cream of tartar until foamy, then gradually sprinkle in 55 g superfine sugar and keep whipping for about five minutes. A firm meringue is what keeps the sponge tall and stops it turning dense. The meringue is ready when it is glossy and smooth, doesn't slide when you tilt the bowl and the peaks curl over slightly.

   Suggested time: about 5 minutes.

   Mark step 3 as done

4. Step 4

   Stir some of the meringue into the yolk batter to loosen it, then pour this mixture into the remaining meringue and use a spatula to scoop from the bottom of the bowl and fold it over. The scoop-and-fold motion keeps as many air bubbles as possible. The batter is ready when it is an even pale yellow, light and fluffy, with no white specks.

   Mark step 4 as done

5. Step 5

   Pour the batter into the pan, level the top, tap the pan gently and bake at 150°C for about 40 to 45 minutes. A long bake at low heat cooks the crumb evenly, keeps it fine and limits shrinking. It's done when the top is pale golden, sounds airy when patted gently and a skewer comes out clean.

   Bake at 150°C for about 40 to 45 minutes.

   Mark step 5 as done

6. Step 6

   Take the cake out, lift it from the pan by the parchment, peel the paper off the sides and let it cool on a wire rack for about an hour. The sponge must be completely cool or the mayonnaise will melt when you spread it. It's ready when both the top and bottom are cool and the surface is no longer damp with steam.

   Suggested time: about 60 minutes.

   Mark step 6 as done

7. Step 7

   Arrange 90 g salted egg yolks on a baking sheet lined with paper, bake at 180°C for about 8 to 10 minutes, then let them cool and crumble them. Baking removes their eggy smell and gives them a rich, slightly fudgy texture. They're ready when they turn deep orange, feel dry to the touch and crumble into fine bits when squeezed.

   Bake at 180°C for about 8 to 10 minutes.

   Mark step 7 as done

8. Step 8

   Whisk 36 g egg yolks with 25 g powdered sugar and a pinch salt, then drip in 150 g vegetable oil a little at a time while whisking constantly, alternating with 10 g lime juice. Adding the oil slowly lets the sauce emulsify into a thick cream without splitting. It's ready when it is thick and glossy and stands up on the tip of the whisk.

   Mark step 8 as done

9. Step 9

   Slice the sponge horizontally into two layers, spread a layer of egg mayonnaise over the bottom one, sprinkle on half of the salted egg yolk and pork floss, then set the other layer on top. The filling in the middle gives every piece a balanced sweet and salty flavor. It's ready when the two layers are stuck firmly together and the filling reaches all the way to the edges.

   Mark step 9 as done

10. Step 10

    Cut the cake into sixteen squares, spread mayonnaise over all their sides, then roll them in 80 g pork floss and sprinkle the remaining salted egg yolk on top. The outer coat of mayonnaise holds the floss in place and keeps the cake from drying out. Each piece is ready when it is fully covered in fluffy golden floss with specks of orange salted egg on top.

    Mark step 10 as done