Place the chicken in a large bowl. Heat a large, heavy sauté pan or cast iron pan over medium heat. Once it's very hot, add half the olive oil and butter, and once they too are very hot, add the onion and a pinch or two of salt. Cook, stirring, until the onion is a deep golden brown, 5 to 7 minutes. Cool slightly, then add to the bowl with the chicken, along with the panko, egg, milk or water, 1 tsp salt, and several grinds of black pepper. Stir to combine evenly with a fork or with clean hands, but don't overmix (no tough meatballs wanted!).
Scoop up about 2 tablespoons of the meatball mixture at a time, and then roll into balls. Wet palms will help it not get stuck all over you. Arrange onto a plate. Repeat with the remaining meat mixture.
Add the remaining butter and olive oil to your same pan over medium heat. Arrange the meatballs in one layer. They will seem soft, and you will think they are going to fall apart. They will not, as long as you don't touch them for 3-4 minutes. Then they should be browned on the bottom and you can gently nudge or flip them over. Continue to roll them around the pan until they're as evenly brown all over as possible. Remove the meatballs with a slotted spoon, and drain them on a plate covered with paper towels (or no paper towels - I just put mine on a clean plate).
Pour in the Marsala or Madeira, and simmer until it's almost completely cooked off, scraping up any browned bits that have stuck to the pan. (I'm pretty generous with my 1/4 cup of wine because it's so good...)
Add the butter to the pan and let it melt, then whisk in the flour. Cook the mixture, stirring, for 1 minute. Slowly add the broth, whisking the whole time to break up any clumps. Add the cream, and bring the mixture to a simmer, then add salt and pepper to taste.
Return the meatballs to the pan, turn to coat them in the sauce, reduce the heat to medium-low, and cover. Let the meatballs simmer in the sauce for 10 minutes. Check a meatball to make sure they're cooked through (should be), but if not, let them simmer a few more minutes.
Bring a large pot of salted water to a boil, and cook the noodle according to package instructions. Most wide egg noodles are done around 6 minutes, 8 minutes max to avoid slimy noodles. Drain.
Place the noodles in a bowl and toss with butter. Add meatballs and pan gravy on top. Garnish with chives.
Source: Smitten Kitchen Everyday