Put the butter and flour into a food processor, and process until grainy.
Divide into single use portions and wrap in plastic wrap. I usually use 60 to 80 g for adults and 15-20 g for children's portion.
When all the mixture is wrapped, store in the freezer. Use for gratins, pasta, soup, etc. Just throw a portion in the pan! Then add milk, soup stock cubes, to taste, and flavor with salt and pepper.
Here I put boiled vegetables in a pan, added frozen beurre manie and milk and cooked it. You just need to add enough milk to reach your desired consistency, so it's easy.
Story Behind this Recipe
My aunt who is a great cook, taught me this recipe.
If the butter is soft, when you blend it it'll become a creamy state, but if you just wrap it in plastic and freeze it, it will be fine. I freeze the butter for a while after cutting it into 1 cm dice.