There was no plan to this purchase at all at the time, but when I got home, I decided to do what I used to do quite regularly while I was at uni - baked with fillings.
I lined a tray with baking paper and pre-heated the oven to 200 degrees C (gas mark 6).
It's important to use mushrooms which have "matured", i. e. where the caps have opened to let the spores out. These are easier to handle, the stems are easier to remove and the cups are easier to peel. So do just that, then place the cups in the tray.
Sprinkle a little salt over them and place your chosen filling inside each. I used cheese for mine - some mystery cheddar-type cheese which I got from the butcher's and which was tasty and I tried some grated parmesan on a couple of the mushrooms.
For Lundulph obviously cheese was not an option, his mushroom cups had pieces of cooked ham with a small piece of butter at the bottom.
The whole thing baked for about 30 minutes, I didn't keep track of time, but I kept checking on the bake regularly. The idea is to let it bake long enough for the mushrooms to bake through completely, yet not to burn the filling.
Delish! Other fillings I used to do at uni were diced bacon, peperoni and butter with crushed garlic. Should definitely be eaten warm.