What are some good creamy curry sauces?

A simple creamy curry sauce is made by blending together 1 tablespoon of melted butter and 1 tablespoon of flour to form a paste. Add 1 tablespoon of curry powder and 1 cup of whole milk or coconut milk. Whisk until smooth and add salt to taste.

To make a creamy curry sauce using sour cream, blend 7 1/2 cups of sour cream with 1/2 cup of lemon juice and 3 tablespoons of curry paste. Add 2 teaspoons of salt, 1 teaspoon of black pepper, 1 teaspoon of curry powder, 1 teaspoon of dried basil, and 1 teaspoon of dried thyme. Whisk all ingredients until smooth and well blended.