1. Steam the chicken breasts until tender. Cool and remove the bones.
2. In a saucepan melt 4 tablespoons butter, add flour and cook stirring for 3 minutes. Add the cream and chicken broth, stirring until smooth and thick. Season with salt, pepper, cheese, Tabasco and herbs. Reserve.
3. In a frying pan sauté the mushrooms in the rest of the butter. Place the chicken in a deep casserole and cover with the mushrooms. Sprinkle with salt and pepper. Add the reserve sauce and cook uncovered in the oven, for 10 minutes.
4. Peel the avocado and cut in slices to decorate.