Preheat oven to 375 degrees and spray a 13×9 baking dish with cooking spray. Chop your onion and garlic.

Heat the olive oil in a large skillet over medium heat. Saute the onion for three minutes, then stir in the garlic and spinach. Continue to saute over medium heat until spinach is wilted, stirring occasionally.

Meanwhile, microwave the corn to package directions. Drain & rinse the beans.

Add the corn, beans, sour cream (or Greek yogurt) and 1 ½ cups of salsa verde into the skillet with the spinach mixture

Stir until everything is nicely combined and the sour cream is melted in. Turn off the heat under the pan.

Pour the remaining ½ cup of salsa verde into the prepared baking dish, using the back of a spoon to spread it out to cover the bottom.

Line the baking dish with three tortillas, tearing the third one in half to fit it on the sides. Top those tortillas with ⅓ of the spinach, corn, & beans mixture, and sprinkle that with ½ cup of the cheese.

Repeat this process until you have used all of the ingredients, noting that the top layer will be just the last three tortillas topped with cheese.

Cover your baking dish tightly with foil, and bake the tortilla casserole at 375 degrees for 20 minutes. Remove the foil and continue baking for another 10 minutes, until cheese is nicely melted and slightly browned.