Marsala is a fortified wine that is made in Sicily in Marsala, hence the name. It is rather like Madeira, and this could make a good substitute if you can't find Marsala. You need the dry wine to cook this dish rather than the sweet dessert wine with the same name.
Although you may think that the dish is Italian, it is in fact Italian-American, and so only dates back to the 19th century. Since then it has become famous around the world, of course.
The basic ingredients are chicken breasts, mushrooms and Marsala wine. It can be a starter, or the makings of a main course, depending on your requirements. You can substitute chicken breasts with veal if you like. The recipe is for four people.
Ingredients
For the flour: 4 oz of flour, salt, pepper and oregano to taste.
4 boneless chicken breasts with the skin removed, and flattened
4 tablespoons of butter
4 tablespoons of olive oil
6 - 8 oz sliced mushrooms
1 cup of homemade chicken stock
1/2 cup of Marsala
salt and pepper to taste
chopped chives to garnish (optional)

Method
Mix the salt, pepper and oregano in a plastic bag and add the chicken pieces one by one. Shake until each piece is coated with the mixture.
Heat the oil in a frying pan and add 2 tablespoons of butter. When this is hot, but not burning, add a chicken piece and fry for three minutes on each side, or until cooked. If you can comfortably get two pieces in the pan, this will speed up the cooking time. Repeat for each chicken piece. Put the pieces on a plate and continue.
Put the a tablespoon of butter in the pan and when it has melted, add the sliced mushrooms and stir. When they are golden brown, remove from the heat and add the Marsala and simmer until it has been reduced by half.
Add the chicken stock and bring to the boil. You may want to add more salt, pepper and oregano to the pan at this stage.
Stir in the remaining butter.
Add the chicken pieces and simmer for about ten minutes.
Garnish with the fresh chopped chives and serve immediately with rice or creamy mashed potatoes.
If you prefer a more spicy taste, add a little hot paprika.
You can use a mixture of mushrooms for this dish but try to use Portobello mushrooms with oyster and button mushrooms.
Enjoy!