โญ Unsweetened Applesauce (Best Gluten-Free Option)
1/4 cup per 1/4 cup onionUnsweetened applesauce works well as a substitute because it contributes moisture and a subtle sweetness that complements the vanilla flavor rather than competing with it. The pectin in applesauce helps retain moisture and improve crumb texture, similar to what onion would provide in terms of moisture content.
To ensure success, use unsweetened applesauce to avoid adding extra sugar that could alter the cake's sweetness balance. Monitor batter consistency as applesauce is wetter than onion; slight adjustments in flour may be needed.
Compared to onion, applesauce enhances the vanilla cake's moistness and tenderness without introducing any savory or pungent notes, making it a seamless substitution in sweet baked goods.