I've been using silocon pans recently for a variety of things --
different sizes, large and small muffins, banana bread loaves, etc.

However, for popovers and Yorkshire Pudds, as someone said, you need to
pre-heat the pan to very hot. This is one case where you need to go
back to metal. For popovers I have special pans where theindividual
cups are separated from each other. For real Yorkshire Pudding I use
old metal pie pans, and get a large result to cut or tear apart.

There seems to be a recent trend on this board to keep confusing
Yorkshire puddng with popovers -- although they have similar means of
preparation, but different ingredients.