There is another chicken marsala recipe on the wiki by Jpfan01.
This is not chicken marsala.
This is definitely not chicken marsala.
Chicken marsala is not gloopy, gooey, rouxy, beige crap. It should be a deep, rich and complex sauce, with no stock in sight. Stock is for people who are too cheap or scared to use an entire half bottle of marsala. Don't be one of those people.
This is based on the Cook's Illustrated recipe, which has been probably the best recipe of theirs I've made -- especially considering how hit or miss they can be. The keys are no stock, using sweet marsala, and caramelizing the tomato paste.
This is the marsala I use. Don't buy the cheapest shit available. Make sure the bottle says sweet, as opposed to dry. If it doesn't say either, it's too shitty to use, buy one that says sweet. This brand makes a half bottle size that is the perfect amount for this recipe. Note, this isn't expensive either, this half bottle is about $6. This is also the pancetta I use for this recipe, from Trader Joe's. I love the homogeneous little bits for sauces, plus it's the right amount for the half bottle of marsala.
Start by prepping about 2 pounds of chicken breasts. Instead of pounding them I just butterfly or slice in half horizontally because it's easier. Season liberally with salt and pepper, then into a pan with a little olive oil over medium to medium-high heat depending on the thickness of your chicken. Get some color on them, do not be afraid of color! Color is your friend. Color is flavor. Do not cook sad white chicken. You will need to do this in 2-3 batches so you do not crowd the pan. When cooked move to a plate.
To make the sauce, add 4 oz of diced pancetta to the pan over medium heat. Do not wipe any delicious chicken fond out of the pan! Let the pancetta render and crisp for a couple minutes, then remove it, leaving a couple tablespoons of fat in the pan.
Into the pancetta fat, add your sliced mushrooms, about a pound. Turn the heat to medium-high and saute a few minutes until browned. If there's liquid pooling in the pan and they're boiling, then turn the heat up. You want them to brown, not boil. Once browned, add a couple tablespoons of tomato paste and 3 cloves of garlic, crushed.
Stir that all around to distribute the tomato paste, then cook it over medium to caramelize it. It'll only take a couple minutes, but it turns darker and will have a nutty, richer smell and kind of coat the bottom of the pan:
Once caramelized, add your marsala, 375 ml or about 1.75 cups. Here's me pretending to be the Pioneer Woman with a pointless pouring-in photo:
Now simmer that for a while (after scraping up any fond of course). Add your cooked pancetta back in at some point. Reduce it until it's as thick as you like, really. We like a lot of sauce, so I left this one a bit thin, but normally I like it a bit syrupy. Once it's reduced nicely, take a couple tablespoons of cold butter and whisk them into the sauce one by one. This will thicken the sauce slightly and add a bit of substance. Squeeze in the juice from half a lemon, and taste. I rarely add salt because the pancetta is usually salty enough. Once the sauce is the way you like it, add your chicken pieces back into the sauce (with any of their juices) to heat through, and top with a good bit of fresh parsley.
Now hopefully this whole time you've been making mashed potatoes and green beans, right? Serve with those things and good bread.
Bonus if you mash your potatoes with the best potato masher in the entire universe which is my absolute favorite thing in my kitchen:
Now go forth and make good chicken marsala and educate others that they've been eating gloppy flavorless shit.