Preheat oven to 450 degrees. Line baking sheet with parchment paper.
Dice mushrooms, peeled sweet potato, and courgette into small bite sized pieces.
Lay mushrooms, diced sweet potato, and diced courgette in single layer, spray top with cooking spray and season with salt and pepper. Roast for 18 minutes, tossing half way, until vegetables are golden brown.
To a large bowl, add roasted vegetables, frozen corn, and spices. Mix well.
Pour tomatillo salsa into shallow dish.
Spray casserole dish with cooking spray.
Ladle 1/2 cup tomatillo salsa onto bottom of dish and spread.
Dip tortilla into tomatillo salsa, then fill tortilla with 2 tablespoons of roasted veggies and wrap tight. Place into casserole dish. Repeat the above step until all tortillas have been filled.
Pour remainder of salsa onto enchiladas. Cover enchiladas with foil and bake for 10 minutes.
Remove foil, sprinkle cheese, and bake for 5 minutes.