Striped Loaf Cake with Vanilla Cream

Preheat the oven to 170°C on the conventional (no-fan) setting. Line the bottom and sides of two metal loaf pans with internal dimensions of 25 × 10 cm and a height of at least 7 cm with parchment paper, without extra fat. Have a mixer, two bowls, a spatula, a rack, a long serrated knife, and two flat trays about 40 × 15 cm that fit in the refrigerator ready. The butter for the cream should be soft but not melted; keep it covered while preparing and cooling the cakes.

Beat all 8 whole eggs with 240 g sugar for about 10 minutes until pale and airy, falling from the beaters in a thick ribbon. Briefly mix in 160 ml oil and 100 ml water on low speed. Sift together 350 g flour and 12 g baking powder, add in two batches, and gently fold with a spatula from the bottom upward. Stop mixing when the dry streaks disappear so you do not lose volume unnecessarily.

Divide the finished batter into two equal portions in separate bowls. Transfer one to the first loaf pan. Add 25 g sifted cocoa and 30 ml milk to the other, mix briefly until evenly colored, and transfer to the second pan. Level both surfaces; the batters do not mix with each other and should leave at least about one third of the pan height empty for rising.

Place both pans side by side on the middle rack, leaving a gap for air circulation, and bake for about 45–50 minutes. The tops should be springy, and a skewer inserted into the center of each cake should come out without wet batter; if needed, bake the affected pan for about 5 more minutes. Cool in the pans for 10 minutes, then lift out with the paper, remove the paper, and leave on a rack for about 80 more minutes until completely cool. Cook the vanilla base as described in the next step while the cakes bake so it cools at the same time as the cakes.

From the 600 ml milk for the cooked cream, pour off 150 ml and mix smoothly with 50 g cornstarch. In a saucepan with a capacity of about 1.5 l, bring the remaining 450 ml milk, 80 g sugar, and 5 ml vanilla to a boil. Stir the slurry again and pour it in, whisking vigorously; once it thickens and bubbles appear, cook over low heat for another 2 minutes, stirring across the bottom. Transfer all of it to a wide container in a layer about 2–3 cm deep, cover its surface directly with plastic wrap suitable for hot food, and cool for about 90 minutes until completely cool but not ice-cold. Do this during baking so both components cool at the same time.

Check that the cooled vanilla base and softened butter feel similar in temperature. Beat 250 g butter for about 5 minutes until airy, then add all the base one spoonful at a time, mixing each addition until combined; the cream should be smooth, without separated liquid. Divide the finished cream into four equal parts: use three to join the slices and the fourth to cover the surfaces of both cakes. Cut each cool cake crosswise into 10 slices about 2.5 cm thick, keeping the end pieces too; do not trim the tops, and do not discard any pieces.

On each tray, arrange 10 slices in a row on their bottoms, alternating 5 pale and 5 cocoa slices. Divide three quarters of the cream equally among all 18 joins, 9 for each assembled cake, spreading it over the cut surfaces and gently bringing the slices together. Spread the remaining one quarter thinly over the tops, sides, and both ends of the two assembled cakes. This makes two cakes about 30–35 cm long, depending on the thickness of the cream; refrigerate immediately for 1 hour so the joins set.

About 40 minutes before the hour of chilling ends, chop 200 g chocolate and place in a bowl. Heat 120 ml cream until small bubbles appear around the edges, pour over the chocolate, wait 2 minutes, and stir until smooth. Cool for about 25–30 minutes, stirring a few times, until the glaze feels cool to the touch but is still fluid. Its cooling overlaps the cakes’ chilling time; do not apply warm glaze to the cream.

After the full hour of chilling, divide all the cool glaze equally between the two cakes and spread over the tops, sides, and ends with light pressure from the spatula. Collect any glaze that drips onto the tray during application with the spatula and spread it back onto the sides; do not discard it. Immediately refrigerate both cakes for at least 3 hours until the cream and glaze are firm.

Divide each chilled cake into about 8 portions, cutting with a sharp knife diagonally at about 45° to the long side, not along the joins between slices. The diagonal cuts reveal several pale and cocoa stripes in each portion. Wipe the knife between cuts so you do not smear the cream, and serve. Return the remaining pieces to the refrigerator immediately.