Stuffed Chicken Breasts

Ingredients
* 4 boneless, skinless chicken breasts (8 oz. each)
* 3 tbsp. vegetable or canola oil
* 8 oz. white mushrooms, sliced thin
* 1 small leek, white part halved lengthwise and chopped (about 1 cup)
* 2-3 cloves garlic, minced or pressed
* ¼ tsp. dried thyme
* 1 tbsp. freshly squeezed lemon juice, divided
* ½ cup dry white wine
* 1 tbsp. chopped fresh parsley, divided
* ¾ tsp. salt
* ½ tsp. pepper
* 1 cup low-sodium chicken broth
* 1 tsp. Dijon mustard
* 2 tbsp. unsalted butter

Directions
1. If your chicken breasts have the tenderloin attached, remove the tenderloins and set aside.  Using a sharp knife, butterfly each chicken breast horizontally, almost all the way through but not quite, leaving the two halves attached like the pages of a book.  Open up the butterflied breasts and lay them out flat.  Place each piece of chicken, laid out flat, in a large zipper-lock bag one at a time. Pound the chicken pieces to ¼-inch thickness.  Trim about 1½ inch from the long side of the cutlets, to remove about 1½ to 2 ounces per piece of chicken.  (Use the reserved tenderloins in place of or in addition to the trimmings to equal about ½ cup total reserved chicken pieces.)  Process the trimmings in a food processor until smooth, about 20 seconds.  Transfer the puree to a medium bowl.  Do not wash out the bowl of the food processor.

2. To make the stuffing, heat 1 tablespoon of the oil in a 12-inch skillet over medium-high heat.  Add the mushrooms and cook, stirring occasionally, until all moisture has evaporated and the mushrooms are golden brown, about 8-11 minutes.  Add an additional tablespoon of oil as well as the leek; cook, stirring frequently, until softened, 2-4 minutes.  Mix in the garlic and thyme and cook just until fragrant, about 30 seconds.  Add 1½ teaspoons of the lemon juice and cook until the moisture has evaporated, about 30 seconds.   Transfer the mixture to the bowl of the food processor.  Return the pan to the heat; add the wine and scrape the pan to loosen browned bits.  Transfer the wine mixture to a small bowl and set aside.  Turn off the heat on the pan.

3. Pulse the mushroom mixture in the food processor until roughly chopped, about five 1-second pulses.  Transfer the mushroom mixture to the bowl with the pureed chicken.  Mix in half of the parsley, and the salt and pepper.  Use a spatula to fold together the stuffing ingredients until well combined.

4. With the chicken breasts laid out flat, spread a quarter of the filling mixture over each of the breasts, leaving a clear edge around the perimeter.  Roll up each breast as tightly as possible without squeezing out the filling and place seam-side down.  Tie evenly with 3 pieces of twine around each chicken breast.

5. Season the chicken pieces with salt and pepper.  Heat the remaining tablespoon of oil in skillet over medium-high heat until just smoking.  Add the chicken bundles and brown on all sides, about 6 minutes per side.  Add the broth and reserved wine mixture to the pan and bring to a boil.  Reduce the heat to low, cover, and cook until a thermometer inserted into the thickest part of the chicken reads 160˚ F, about 12-15 minutes.  Transfer to a plate or cutting board and tent loosely with foil.

6. While the chicken is resting, whisk the mustard into the cooking liquid.  Bring the heat to a high simmer, scraping the pan bottom to loosen browned bits.  Simmer until reduced to ½ cup, about 7-10 minutes.  Off the heat, whisk in the butter, remaining parsley and lemon juice.  Season with salt and pepper to taste.  Remove the pieces of twine, slice the chicken pieces on a slight diagonal, and serve with sauce spooned over the top.

Notes
Hannah picked this out from my Cook's Illustrated cookbook - one of my favorite books in my collection.  I didn’t have garlic on hand (gasp!), so I substituted ¼ tsp garlic powder.  If you read this recipe and think maybe you might skip making the sauce – don’t!  The sauce is amazing!!! Also, one of my chicken breasts really became a sight while pounding it out, so when we stuffed it and rolled it, I used 5 pieces of twine to keep it together.  It certainly wasn't the most beautiful one in the pan, but it still tasted fabulous.  And don't be scared of leeks if you've never used them before...they are basically a really big green onion!  The kids and adults loved this meal.  We served it with rice and asparagus.  This would be a great meal to serve to company.