Japanese Roll Cake

Instructions

1. Preheat the oven to 375°F (190°C) and line the pan with parchment, letting it come up the sides. Put the whole milk and unsalted butter in a small bowl and warm until the butter melts, about 30 seconds in the microwave; keep warm.
2. In a large heatproof bowl, whisk the eggs and 80 g granulated sugar. Set over a pan of barely simmering water and whisk until the mixture feels warm, about 100°F (38°C). Remove from the heat and beat with an electric mixer on high until pale, tripled in volume and thick enough to fall in a ribbon that holds for a few seconds, 6 to 8 minutes. Beat on low 1 minute more to even out the bubbles.
3. Sift the cake flour over the foam in two additions, folding gently with a spatula until no flour shows.
4. Stir a large spoonful of the batter into the warm milk and butter until blended, then fold this mixture back into the batter until just combined.
5. Pour into the pan, smooth to the corners with a scraper and tap the pan once on the counter. Bake until golden on top and springy when pressed, 11 to 13 minutes.
6. Drop the pan once from about 4 inches (10 cm) onto the counter to stop shrinking, lift the cake out by its parchment onto a rack, loosen the paper from the sides and lay a clean sheet of parchment loosely over the top. Cool completely, about 40 minutes.
7. Whip the heavy cream with 20 g granulated sugar and the vanilla extract to firm peaks, 2 to 3 minutes.
8. Flip the sponge onto a fresh sheet of parchment, browned side up, and peel off the baking paper. Make a few shallow cuts across the edge nearest you, about 1/2 inch (1 cm) apart, and trim the far edge on a slant. Spread the cream thickly over the near half and thinly toward the far edge.
9. Using the parchment to help, roll the cake firmly away from you, ending with the seam underneath. Wrap tightly in the parchment, twist the ends and refrigerate seam side down until set, at least 2 hours. Trim the ends and slice with a warm, dry knife.