Preheat oven to 180C
Place the mushrooms, gill-side up, onto a greased oven tray.
Season with salt and pepper, then sprinkle with the thyme, then drizzle with olive oil and roast for 20 minutes until the mushrooms become tender.
In a bowl, mix together the tuna, feta, cream cheese and then spoon mixture onto the mushrooms.
Sprinkle with the breadcrumbs, then return to the oven to bake for another 10 minutes.
Serve once cooled down.