Milk + Lemon Juice (Best Option)
1 cup milk + 1 tablespoon lemon juice (let sit 5 minutes)This substitute works because the lemon juice acidifies the milk, creating a similar pH to buttermilk which helps break down proteins in the chicken, tenderizing it and enhancing flavor. The acidity also helps the filling thicken properly when cooked.
For best results, use whole milk for richness and allow the mixture to sit for at least 5 minutes to curdle slightly before adding to the filling. Avoid using skim milk as it may result in a thinner filling.
Compared to buttermilk, this substitute yields a very similar texture and flavor profile, maintaining the creamy, slightly tangy balance essential for a classic chicken pot pie.