Place mushrooms, tomato, unpeeled garlic cloves, butter and herbs (if using) in a large oven proof dish. Cover with a lid or foil.

Turn oven to 150C (300F) and bake mushrooms for 1 hour.

Stir mushrooms and remove the lid. Bake for another 1 to 1 1/2 hours or until the sauce is reduced and the mushrooms are lovely and deep golden. Taste and season.

Either serve hot or cool and refrigerate or freeze.