Sour Cream (Best Option)
1:1 (replace Greek yogurt with equal volume of sour cream)Sour cream works well because it has a similar fat content and acidity level as Greek yogurt, which helps activate baking soda or powder for leavening and contributes to a moist crumb. The tanginess also enhances the chocolate flavor by balancing sweetness.
For best results, use full-fat sour cream and measure it exactly to avoid altering batter consistency. Avoid low-fat versions as they may reduce moisture and richness.
Compared to Greek yogurt, sour cream produces a similarly tender and moist cake with a slightly richer mouthfeel but nearly identical flavor profile, making it the most seamless substitute.