Ingredients :

• Plain yogurt — This is the boss here — not just for the taste, but because its container becomes your measuring unit for the entire recipe. Use a classic whole milk yogurt, 125g, the standard plastic cup. The brand doesn’t matter. Avoid 0% fat versions: they result in a cake that is somewhat dry and lacks character.
• Unsweetened cocoa powder — Truly unsweetened, and it matters. Use pure cocoa powder like Van Houten, not the chocolate mix used for morning milk. Real cocoa provides a slightly bitter undertone that balances the vanilla. With sugary powder, it becomes cloyingly sweet.
• Vegetable oil — Sunflower, canola, it doesn’t matter — the key is that it’s neutral in taste. No olive oil. This is what gives the cake its characteristic moistness, quite different from a butter-based pound cake that dries out by the next day.
• Vanilla extract — A few drops are enough. A packet of vanilla sugar also works — but liquid extract gives a bolder, more floral note. Both work; choose based on what you have on hand.