Separate all mushroom stems and caps, and set caps aside. Coarsely chop mushroom stems, then simmer in chicken stock, covered, for one hour. Strain mushroom stems from chicken broth. Reserve the broth and discard stems. Return broth to pot and set aside.

In the meantime, cut mushroom caps into a half-inch dice. Heat oil in a large skillet, and sauté shallots and garlic until softened, about three minutes. Add thyme, rosemary, salt, and pepper and cook for two minutes.

Add diced mushrooms and reduce heat to low. Cook gently until most of the liquid is released and evaporated. If using fresh herbs, remove thyme and rosemary sprigs.

Raise heat and add Cognac. Cook until alcohol is mostly reduced and mushrooms start to turn a little golden on the edges.

Add mushroom and shallot mixture to the strained broth and heat gently.

Add creamer and chives. Serve warm, topped with frizzled onions if desired.

Place thinly sliced onion into a baking dish. In a small bowl, mix milk with vinegar and stir. Pour over onion and soak for at least an hour.

Combine flour, salt, and cayenne pepper. Set aside.

Heat oil in a large pot over medium-high heat, until it reaches 375 degrees Fahrenheit.

Take a handful of onions and shake off excess liquid. Coat with flour mixture and shake off excess. Fry for about two to four minutes until golden brown. Drain on paper towels.

Repeat with remaining onions. Make sure to keep oil at correct temperature for each batch.