Yesterday for a neighborhood BBQ I decided to incorporate both Food52 themes into the dinner: your best cucumber, and your best use of lemon, thyme, and the grill. Luckily I am up on the Cape and I actually have access to a grill, so I had to give it a shot. This chicken dish was born out of my fear and loathing of dry chicken cooked on the grill, so I pounded it thin, stuffed it with spinach that I had previously sauteed with garlic, pancetta, and lemon juice, marinated it in oil, thyme, lemon, and pepper, and grilled it quickly on both sides until cooked through. The dish is finished with a summery gremolata of...what else? Lemon zest and thyme! It was a big hit with the neighbors. —lechef
Trim any excess fat from the chicken breasts. Using a sharp knife, make an incision (for stuffing) along the thicker leading edge of the breast. You will want to cut as deeply as you can to create a "pocket" in the breast without slicing out the other side, or the ends. Repeat for all 4 breasts.
Using a frying pan, pound the breasts until they are about 1/2 inch thick. Don't be too forceful, because you want to make sure that you keep your pocket intact. Alternatively, if you are very confident in your knife skills, you can pound them thin first and then make your incisions. I only thought of cutting the pocket first after I had already pounded my chicken breasts thin, and I was still able to cut my pockets without too much trouble.
Season the breasts with salt and black pepper, and put in a dish with the olive oil. Toss with 1 tablespoon lemon juice and 1 tablespoon of the chopped thyme, and allow to marinate for at least an hour.
Meanwhile, in a skillet, heat the butter over medium heat (you can use olive oil if you want to be healthier, of course). Add the pancetta and cook for 2-3 minutes to brown. Add the garlic, and cook for 3 minutes. Add the raw spinach and 1 tablespoon lemon juice to the skillet, and allow to cook down until fully wilted. Remove from heat, allow to cool, and chop the spinach to break up any large stems. Set aside.
When ready to cook, heat your grill. Stuff each chicken breast with as much of the spinach mixture as it will hold, but don't overdo it. Otherwise it will just come out on the grill. Grill for about 6 minutes per side, until cooked through. These will cook relatively quickly since they are pounded thin, so keep a close eye on them. The spinach stuffing keeps them nice and moist as well.
To make the gremolata, mix 1 tablespoon thyme and 1 tablespoon lemon zest (or any 1 to 1 ratio if you have more zest). Remove chicken from grill, sprinkle liberally with gremolata, and serve. Enjoy!