- Heat 2 Tbsp. of oil in a large skillet set over medium-high. Add onions and mushrooms and cook until mushrooms are tender and moisture has evaporated from them, about 6 minutes. Mix in garlic and sage; cook 1 minute more. Transfer mushrooms to a bowl and cool to room temperature.
- Bring 3” of water to a boil in a pot set over medium-high. Trim off the tough stems and centre ribs from kale leaves and discard or compost. Tear leafy parts into large pieces, and then boil 3 minutes. Drain kale, cool in ice-cold water, and then drain again. Squeeze out as much water as you can from the kale. Now coarsely chop.
- Add kale, cheese, panko, salt and pepper to the mushrooms and toss to combine.
- To help chicken sit flat as it cooks, remove the fillet (a thin strip of loosely attached meat) running down the centre of each breast, by gently pulling them off. Save these pieces of breast – they could be frozen - for another use, such as slicing for a stir-fry.
- Cut a deep horizontal slit through thickest portion of each chicken breast, without cutting all the way through. Open the chicken breasts up where you cut them. Sprinkle insides with salt and pepper.
- Now divide and tightly stuff each breast with the mushroom mixture. Firmly press each chicken breast back together to help hold the filling inside. It’s ok if some filling shows out the side.
- Preheat oven to 375˚F. Line a baking sheet with parchment paper. Heat remaining 2 Tbsp. oil in a large skillet set over medium-high. Carefully sear each breast until light golden, about 2 minutes per side. Set chicken on the baking sheet. Push any filling the fell out back into the chicken. Season top of chicken with salt and pepper. Now bake chicken 20 minutes, or until cooked through.
Note: Coarse-looking, dried sage leaves are available in our bottled herb and spice aisle.
Options: Instead of Gouda, try another type of tangy cheese, such as cheddar, Swiss or Asiago. Instead of kale, use 1/2 cup of well-drained and squeezed cooked spinach here. If desired, roast vegetables to serve with the chicken alongside the breasts as they cook. These could include thin slices of squash, par-boiled miniature potatoes, and blanched green cauliflower florets. Coat vegetables with a little olive oil and season with salt and pepper before roasting.