Kale and Caramelized Onion Stuffed Mushrooms

What once was a kale and onion grilled cheese sandwich has been transformed into one of my favorite grain free meals.... the stuffed porotbello mushroom.

This recipe also includes two of my favorite ingredients....cheese and, I can't believe I'm about to say this, kale. Something I once turned my nose up, then managed to choke down on an as needed basis, and now genuinely enjoy. (Cue the la cliche jokes.)

Ingredients:
4 portobello mushrooms, stemmed
4 medium kale leaves, stems removed
2 tsp olive oil
2 medium red onions, cut into 1/2 inch slices
1/4 tsp freshly ground black pepper
1/8 tsp kosher salt
1 tbsp red wine vinegar
1 oz finely grated parmesan cheese,
divided (about 1/4 cup)
3.5 oz raclette or gruyere cheese



Directions:
Preheat oven to 300 degrees. Bring a small pot of water to a boil; add kale. Remove from heat; let stand 4 minutes or until kale is bright green. Drain; rinse kale under cold water until cool. Pat leaves dry.
Heat a skillet over medium-high heat. Add oil; swirl to coat. Add onion, pepper and salt. Cook 10 minutes or until onion is tender and browned, stirring frequently. Remove from heat; stir in vinegar, tossing to coat. Coarsely chop onion.
Spray each side of mushrooms and place cut side down on a baking sheet. Cook for 5 minutes. Flip mushrooms and top each with 1 kale leaf, 1/4 onion mixture and 1/4 cup cheese. Bake for 5 more minutes or until cheese melts.