6 oz. fresh blackberries,
2 tsp. red wine vinegar
2 tsp. olive oil, plus more for pan
1 tsp. honey
1 tsp. fresh thyme leaves
Salt and pepper, to taste
2-3 chicken boneless skinless chicken breasts
1 tsp. herbes de Provence
Sandwich buns, split
1 cup baby spinach leaves
4 oz. brie, thinly sliced
In a small bowl, combine the blackberries, red wine vinegar, olive oil, honey, and thyme leaves. Season lightly with salt and pepper. Toss well with a fork, mashing berries slightly but leaving most intact. Set aside.
Holding the chicken breasts in place with tongs, butterfly them lengthwise to produce two thinner halves. Season both sides of the chicken pieces with a sprinkle of herbes de provence, as well as salt and pepper. Place a large skillet (preferably cast iron) over medium-high heat and coat lightly with olive oil. When the pan is hot, add the chicken pieces and cook, turning once during cooking, until both sides are browned and the center registers 160˚ F on an instant read thermometer. Transfer to a plate to rest and tent with foil.
Meanwhile, preheat the oven to 400˚ F. Place the split sandwich buns on a baking sheet, cut sides facing up. Layer one half of each bun with baby spinach leaves and sliced brie. Transfer the baking sheet to the oven and let bake just until the naked half of the bun is toasted and the brie is melted. Remove from the oven, place a piece of chicken on top of the brie on each bun, and spoon some of the blackberry mixture over the chicken. Close the sandwiches with the other half of the each bun and serve immediately.