2 tablespoons (30 ml) olive oil
3 pounds (1.4 kg) chicken breasts (6 small breasts)
2 teaspoons (14 g) salt, divided
1 teaspoon (2 g) black pepper, divided
2 poblano peppers, diced
2 portobello mushrooms, diced
2 green onions, thinly sliced
1 egg
1 teaspoon (2 g) chili powder
1 cup (115 g) smoked cheddar cheese
Heat oven to 400 degrees Fahrenheit (204 degrees Celsius). Use a small amount of olive oil to grease a 9-by-13-inch (23 by 33 cm) baking pan.
One at a time, place chicken breasts between two pieces of plastic wrap and pound to 1/4-inch thickness, working from center to edges. Season with 1½ teaspoons salt and ½ teaspoon pepper.
Heat olive oil in skillet over medium-high heat. Add mushrooms and cook for about 5 minutes, until they begin to brown and most of the liquid has evaporated. Add peppers and onion and continue to cook for another 3 to 4 minutes, until softened. Pour into a medium bowl. Add remaining ½ teaspoon each of salt and pepper, egg and cheese and mix thoroughly.
Place about one-sixth of the filling in the center of each breast, wrapping meat tightly around filling. Secure seam with a toothpick, or tie each breast with a piece of twine. Brush outsides of breasts with remaining olive oil and place in prepared baking dish, spacing evenly. Bake 30 minutes. Cool for 5 minutes. Remove twine or toothpicks and serve.