Heat a large, nonstick skillet over high heat with the EVOO, about 2 turns of the pan, and the butter. Toss in the mushrooms and cook 5-6 minutes, until theyre golden brown and slightly crispy.
Add the garlic to the pan and toast slightly, then toss in the shallots, thyme and bay leaf. Season the veggies with salt and freshly ground black pepper and cook 2-3 minutes, until the shallots are tender.
Sprinkle the flour over the veggies in the pan and cook for about a minute. Gently whisk in the chicken stock and cream, and bring to a bubble. Allow the gravy to simmer, stirring frequently, until it has thickened up.
Stir in the chopped rotisserie chicken and nutmeg, and taste to see if the mixture needs any more salt or freshly ground black pepper. Simmer about a minute more to heat the chicken through. To serve, ladle the finished gravy into coffee mugs and top each one off with a biscuit.