Yorkshire Pudding

I don't understand Yorkshire Pudding. Let me explain...

Yorkshire Pudding is cooked by pouring a thin batter made from milk (or water), flour and eggs into oiled then preheated baking pans or muffin tins.

Yorkshire Puddings are a staple of British cuisine and are found frozen in the grocery store and on platters of food at the pub.

But why is it called Pudding? It’s a tall (no less than 4 inches tall), fluffy, yet rather thick and hearty pastry that’s cooked in a muffin tin so it always is the shape of a cup or a bowl with a hallow middle, but you don’t but put anything inside the middle space, so why is it shaped like a bowl? Why not fill the batter in completely and have it be a regular biscuit shape?

The name… Yorkshire. This I understand as self-explanatory, it is from Yorkshire. Pudding… this is a mystery. The Brits often refer to Dessert as Pudding. If you see “Puddings” on the menu, it doesn’t mean what Americans would think of like Jell-o pudding snacks. The term Pudding encompasses all Dessert type foods including a mousse, which is rather pudding like, or a cake, a gelato, a brownie etc….

So… why do they call this bowl shaped biscuit served with the traditional Sunday roast lunch a “Pudding”?