This recipe is one you can prepare before your guests arrive. The sauce starts with a packaged mix that is truly a "take home miracle". The pasta can be cooked in advance and you could use cooked chicken breasts in place of baking the chicken.
Pre heat the oven to 350
Place chicken breasts in a 8 1/2 by 11 pyrex baking dish. Season with salt and pepper. Place boullion cubes in a 4 cup measure and add water. Microwave on high for 90 seconds, then stir to dissolve the cubes. Add Marsala wine and lemon juice. Pour half the liquid over the chicken breasts. Cover and refrigerate for up to 6 hours. Reserve the remaining liquid for the sauce.
To cook the pasta, bring 8 cups salted water to a boil. Add the pasta and boil about 8 - 10 minutes or until tender. Drain and toss in olive oil to prevent sticking. You will re heat the pasta just before serving.
To make the sauce, add enough water to the reserved broth and wine to make a total of 3 cups. Place in a saucepan and whisk in the contents of 3 packages demi glace powder. Place over medium high heat, stirring constantly, and bring to a boil. Reduce the heat and simmer, stirring about one minute. Whisk in the butter, mushrooms and sun dried tomatoes. (Be sure mushrooms are completely drained, or you will add water to the sauce)
Bake the chicken in preheated oven, or, if using cooked chicken, heat the same amount of chicken broth and Marsala wine in the microwave, then pour over the chicken and bake for 15 minutes to re heat. Cover with foil to keep warm.
Have a saucepan of boiling water ready. Place the pasta in a collander and pour boiling water over the pasta to reheat. Divide among 6 serving plates. Remove chicken breasts from the liquid and place atop each pasta serving. Re heat the sauce and pour over the top. Garnish with a sprig of fresh parsley.