Sour Cream (Best Option)
1:1 (1/4 cup sour cream per 1/4 cup Greek yogurt)Sour cream closely mimics the moisture and acidity of Greek yogurt, which is important for activating baking soda or powder in sugar cookies, contributing to proper rise and texture. Its fat content also helps keep the cookies soft and chewy.
When substituting, use the same amount as Greek yogurt. Ensure the sour cream is full-fat for best results, as low-fat versions may dry out the dough slightly. Mix thoroughly to incorporate evenly.
The final cookies will have a very similar texture and flavor profile, with a slight increase in richness and tang that complements the sweetness well.