This is an English classic also known as popovers and usually cooked around a roast or in beef fat. But after I became a vegetarian at 12 years old, my English grandmother, while she was concerned I wouldn't get enough protein, would always cook a few in muffin tins in oil for me.
3 tablespoon butter or oil
1 cup milk
1 cup minus 1 tablespoon flour
½ tsp sea salt
Cut each tablespoon of butter into 4 equal pieces. Place each piece of butter in the 12 cups of a muffin tin. Place the muffin tin in a 450º preheating oven to melt butter (do not brown or burn!).
Whisk together eggs and milk. Whisk in flour and salt until well combined. Pour batter evenly into the hot muffin tin, each cup about half full.
Bake for 15 minutes (10 with convection). Lower heat to 350º and bake another 5-10 minutes until golden brown.
Makes 12 popovers