This looks like French onion soup but has the rich mushroom flavour instead of onion. It is...
Crimini Brown Mushrooms
Crimini mushrooms are similar in size and shape to white mushrooms, except that they have a darker cap. When it comes to taste, Criminis have a firmer texture and heartier flavour, making them ideal for grilling, stuffing, and stir-frying.
How to purchase
Look for a firm, even coloured, symmetrical cap with closed gills. Colours range from a light tan to a rich brown.