Seafood Enchiladas

Melt 14 g butter in a saucepan over medium heat. Add 150 g diced onion and cook until softened, about 5 minutes.

Sprinkle 48 g flour over the onion and stir constantly for 2 minutes to form a roux.

Gradually whisk in 202 g cream and 101 g cream, stirring until smooth and thickened, about 8 minutes. Season with 3 g salt.