Put almost 1 teaspoon of the butter (or beef drippings) into 4 muffin cup sections of a 12-hole Yorkshire pudding tray or muffin tray and put into the oven on the top shelf .

Preheat oven to 425 with pan in place.

In a blender, combine the egg, milk, flour, and salt. Blend until well combined and place in the refrigerator until ready to use (allow to rest for at least 30 minutes).

As soon as you take the tray from the oven, pour in the batter to three-quarters fill the tins (it should sizzle) and immediately put back into the oven.

Bake until the Yorkshire puddings are well risen, golden brown and crisp, 15 to 20 minutes. Don't open the oven door until the end or they might collapse.