Bring a nonstick skillet to medium high heat and coat with cooking spray. Add in chopped mushrooms.
Once browned, add in the ground meat. Continue cooking until cooked through and most of the liquid has evaporated. Season with salt and pepper and stir in the marinara sauce until it’s coated but not soupy. Remove from heat. Preheat the broiler.
On a baking sheet, lay out each tortilla. Sprinkle with a little bit of cheese, then top with meat, more cheese and some green peppers.
Place the baking sheet in the top third of the oven, under the broiler. Cook for 3-4 minutes or until the cheese is melted and the tortillas begin to crisp up. Monitor closely.
Serve open face or folded up taco style!