Preheat the oven to 350ºF.

In a large skillet or Dutch oven add 4 tablespoons of the chicken fat and sauté bell peppers and celery until softened, about 6 minutes. Add the thyme sprigs and the remaining chicken fat along with the mushrooms, green onions, garlic and cook until the vegetables are softened, 4 to 5 minutes. Add the farfel or cous cous and cook, stirring, until toasted, 2 to 3 minutes. Add 3 cups of the broth if you are using farfel, (or 4 cups if you are using cous cous) and bring to a boil. Season to taste with salt and pepper. In a small bowl, whisk the egg yolks into the remaining broth and stir it into the farfel or cous cous. Pour into a lightly greased 3-quart casserole and bake (covered) until the farfel is set or until the cous cous has absorbed the liquid, about 30 minutes.

Remove from the oven and serve hot or warm, garnished with the parsley.