Can you substitute sour cream for heavy in a spinach gratin?

While you can substitute sour cream for heavy cream in some recipes, it may not be the best choice for a spinach gratin. Here's why:

1. Different Texture: Sour cream is thicker than heavy cream, so it will create a different texture in the gratin. Heavy cream provides a creamy, velvety sauce, while sour cream can make the dish grainy or curdled.

2. Flavor Profile: Sour cream has a tangy flavor that can overpower the delicate taste of spinach. Heavy cream, on the other hand, has a neutral flavor that allows the spinach to shine.

3. Cooking Properties: Heavy cream is more stable than sour cream when heated, making it less likely to curdle or separate. Sour cream is prone to curdling, especially if exposed to high heat or acidic ingredients.

4. Fat Content: Sour cream has a higher fat content than heavy cream, which can make the gratin richer and heavier. If you're looking for a lighter dish, heavy cream is the better option.

If you don't have heavy cream on hand, you can try using a combination of milk and cornstarch to create a sauce similar to heavy cream. Mix 1 cup of milk with 1 tablespoon of cornstarch and cook over medium heat, stirring constantly, until the mixture has thickened and reached the desired consistency. This cornstarch slurry can be used as a substitute for heavy cream in many recipes, including gratins.